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Fattah, I.M.R. Real Driving Emissions. Encyclopedia. Available online: (accessed on 20 April 2024).
Fattah IMR. Real Driving Emissions. Encyclopedia. Available at: Accessed April 20, 2024.
Fattah, I. M. R.. "Real Driving Emissions" Encyclopedia, (accessed April 20, 2024).
Fattah, I.M.R. (2021, July 31). Real Driving Emissions. In Encyclopedia.
Fattah, I. M. R.. "Real Driving Emissions." Encyclopedia. Web. 31 July, 2021.
Real Driving Emissions

Air pollution caused by vehicle emissions has raised serious public health concerns. Vehicle emissions generally depend on many factors, such as the nature of the vehicle, driving style, traffic conditions, emission control technologies, and operational conditions. Concerns about the certification cycles used by various regulatory authorities are growing due to the difference in emission during certification procedure and Real Driving Emissions (RDE). Under laboratory conditions, certification tests are performed in a ‘chassis dynamometer’ for light-duty vehicles (LDVs) and an ‘engine dynamometer’ for heavy-duty vehicles (HDVs). As a result, the test drive cycles used to measure the automotive emissions do not correctly reflect the vehicle’s real-world driving pattern. Consequently, the RDE regulation is being phased to reduce the disparity between type approval and vehicle’s real-world emissions. According to this review, different variables such as traffic signals, driving dynamics, congestions, altitude, ambient temperature, and so on have a major influence on actual driving pollution. Aside from that, cold-start and hot-start have been shown to affect on-road pollution. Contrary to common opinion, new technology such as start-stop systems boost automotive emissions rather than decreasing them owing to unfavourable conditions from the point of view of exhaust emissions and exhaust after-treatment systems. In addition, the driving dynamics are not represented in the current laboratory-based test procedures. As a result, it is critical to establish an on-road testing protocol to obtain a true representation of vehicular emissions and reduce emissions to a standard level. The incorporation of RDE clauses into certification procedures would have a positive impact on global air quality. 

air pollution real driving emission driving cycles portable emission measuring systems air quality

1. Introduction

As the world progresses, technological development has resulted in the availability of machinery, which translated into the development of a machine-based industry, resulting in increased emissions. The imposed travel restrictions worldwide in 2020 due to the COVID-19 pandemic has resulted in a 6% reduction in energy demand compared to 2019 [1]. Despite the fact that the global energy-related CO2 emissions declined by 5.8% in 2020, they still remained at 31.5 Gt, which contributed to CO2 reaching its highest-ever average annual concentration in the atmosphere of 412.5 parts per million in 2020—around 50% higher than when the industrial revolution began [2]. While it would be ideal to have the latest data, at the time of publishing the report ‘Emissions by sector’ [3] (September 2020), the most recent comprehensive data set were available for 2016. The authors reported that the global greenhouse gas (GHG) emissions were 49.4 billion tonnes (Gtoe) of carbon dioxide equivalents (CO2eq) at that time [3][4] (CO2eq sums all of the warming impacts of the different greenhouse gases together. To calculate the CO2eq of non-CO2 gases, their mass was multiplied by their ‘global warming potential’ (GWP). GWP measures the warming impacts of a gas compared to CO2). They reported that the energy sector contributed almost 3/4th of the total GHG emissions (73.2%) [3]. Of this 73.2% emitted by the energy sector, the majority of contributors were the industry, transport and building sectors which consisted of 24.2, 16.2 and 17.5%, respectively (Figure 1). About 73.5% of transport sector emission is contributed by ‘road transport’, followed by ‘aviation’ and ‘’shipping’ at 11.7 and 10.5%, respectively, as shown in Figure 1. A report claims that to achieve net-zero-emission by 2050; the world needs to maintain a drop in emissions of around 5% each year from now forth [5].
As of 16 March 2021, the total number of confirmed COVID-19 cases had surpassed 183 million, with the pandemic affecting more than 192 countries/regions [6]. COVID-19 has now resulted in the death of over 3,962,550 people [6]. More than a year into the pandemic, the countries worldwide are still struggling to combat the spread of COVID-19, which is hurting the economy. Thus, when the world returns to a new normal state, it will be hard to keep the energy demand low and reduce GHG emissions due to the sudden increase in social and economic activities. Decisive actions are needed to reduce transport emissions to achieve the zero-emission target. Thus, the vehicles that are used for everyday transport must follow the emission standards set by the regulatory body. Figure 2 shows the timeline of emission standards for passenger cars for the United States, Europe, China and Japan [7].
There is ongoing concern about public health owing to air pollution caused by vehicle emissions. It is well-recognised that air pollution is a primary risk factor for chronic non-communicable diseases [8]. Pollutants carry microorganisms that are highly invasive to humans, affecting the immune system and making people more susceptible to pathogens [9]. The COVID-19 pandemic has also manifested the importance of a healthy environment. Vehicle emissions depend on the vehicle nature and mode of operation factors such as driving style [10], traffic conditions [10], fuel quality and specifications [11], the technology behind the vehicle design, such as emission control technology [12][13], and ambient conditions [13][14]. These factors determine the number and amount of pollutants emitted during the driving interval and cannot be replicated through engine test cycles. Hence, these pave the way for vehicle development and the consequent recent advance of vehicle technology and emission control strategies. This also depends on driving behaviour and traffic conditions—several factors such as changing lanes, overtaking or merging result in increased engine loads [15]. As a result, the engine operates in a rich fuel-air ratio, and thus emissions are increased [16]. Furthermore, vehicle acceleration and speed also affect emissions. Vehicle acceleration significantly impacts CO and HC emission, especially at high speeds and low vehicle speed in congested traffic results in increased emission. Auxiliary loads such as air conditioning systems can increase CO and NOx emission and sometimes double emissions. Road type is another critical factor, e.g., hill ascents result in high NOx emissions. Also, the horizontal curvature of roads and roundabouts increases engine load and thus results in increased emissions. Thus, the gap between regulated vehicle emissions from certification procedures and real-world driving emissions has become increasingly wider [15][17]. The inclusion of real driving test procedures can attenuate the discrepancies between emission values determined in laboratory tests and emission values produced during on the road driving because they take greater acceleration into account, along with gradients, stop-and-go, or higher speeds. Emission measurements under real driving conditions can significantly contribute to improving the air quality of the world. The development of an RDE test cycle has been thoroughly discussed in the literature, with many methods suggested [18][19][20]. It is to be noted that this review article does not focus on engines for non-road applications that constitute: handheld portable devices (lawnmowers, grass mowers, chainsaws, hedge trimmers, twig choppers, snow removal machines, and devices applied in forestry), power generators, and non-road vehicles also referred to as Non-Road Mobile Machinery (NRMM) [21]. The NRMM vehicle group includes construction machinery, farm tractors and machines, and special-purpose machinery [22][23]. This group of vehicles is subject to separate regulations on exhaust emissions which was detailed by Waluś et al. [24]. Emissions from such machinery are also tested against standards during approval; however, these tests are conducted in real operating conditions [23][25][26][27].
Previous reviews on emission test procedures generally focused on various aspects of vehicle certification procedures. For example, Mahlia et al. [28] reviewed motor vehicle fuel efficiency research procedures in order to establish a test protocol to endorse Malaysia’s fuel economy standard, labelling, and other associated services. They came to the conclusion that Malaysia should use the Japanese JC08 fuel economy evaluation protocol for motor vehicles. Hooftman et al. [29] studied the history of European emission regulations and offered a comparative overview of the European market’s approaches with the approaches of other major automotive markets around the world. They concluded that a significant revision of the European regulatory system governing automotive emissions is needed. Agarwal and Mustafi [30] conducted a more recent study of real-world vehicle emissions, focusing on the more recent methodologies for monitoring vehicular emissions under real-world driving conditions. This report would concentrate on research that has contributed to developing the RDE test protocol, which aims to minimise the gap between type-approval and real-world driving emissions.

2. Vehicle and Engine Test Cycle Basics

Vehicle emissions are one of the main sources of greenhouse gas (GHG) emissions in modern cities, leading to air pollution [31]. The rising number of passenger cars, especially in the last decade, has resulted in a complicated traffic issue with significant implications in terms of vehicular emissions [32][33]. Since the early 1960s, vehicles’ compliance with emission regulations has been checked using standardised tests [34]. These have been known as driving/drive cycles, test cycles, or transient cycles. Even though these three terms are often used in the literature interchangeably, they might not mean the same test procedures or parameters. Driving test cycles involve testing the whole vehicle and typically comprise of a series of data points representing a speed-time profile that is representative of urban driving [35][36][37][38]. In particular, the test cycle consists of a series of test points, where the vehicle or engine in question has to follow a certain speed at each point. Thus, in this regard, test cycles are primarily classified as (a) chassis dynamometer cycles used for vehicle testing and (b) engine dynamometer cycles used for engine testing. Engine tests cycles are carried out for exhaust emission certification procedures for heavy-duty and off-road vehicles as it is often impractical to put those vehicles on a chassis dynamometer. These tests are performed in an engine test-bed following a pre-determined speed-time pattern which typically lasts from a few minutes to 30 min, with even lengthier cycles being developed. Applying transient cycles for the test cycle has an advantage of a relatively wide range of operations in terms of load and speed, which also accounts for serious discrepancies encountered during sudden load and speed changes [39]. It should be noted that the transient cycle is typically performed to determine the overall amount of exhaust emissions and fuel consumption rather than to identify the particular conditions or sections where these are produced.
Standardised automotive drive cycles and engine duty cycles are important development techniques. These cycles include common metrics for measuring efficiency in assessing compliance with an emissions level and a fuel consumption/economy performance standard and comparing the performance of two technologies [40]. In many parts of the world, these cycles serve as a standardised measurement of vehicles’ performance during type approval, i.e., certification procedure. In fact, emission standards heavily rely on the employed driving cycle and test procedures. Manufacturers often design and calibrate their vehicles using the test procedures standards to meet the standard. Comparing vehicles/engines from different manufactures are made possible through these standardised tests. Other applications of driving cycles include providing a long-term premise for design, tooling and marketing to vehicle manufacturers [41]. These also help traffic engineers in designing traffic control systems considering traffic flows and delays [42]. Environmentalists can negotiate specific driving patterns to reduce pollution generated based on these cycles [43]. Another use for driving cycles is in automotive modelling, where they can be used to estimate pollutant emissions and fuel consumption of cars in specific urban areas [36][42].

3. Legislative Test Drive Cycles for the Emission Type Approval

Regulatory and certification authorities often use two basic philosophies when designing a driving cycle [15]. In the first philosophy, the driving cycle consists of a sequence of repetitions of a combination of several vehicles operating modes that are representative of driving models. Based on this theory, the Economic Commission for Europe (ECE) and Japanese cycles were established. On the other hand, the driving cycle is a simulation of a real route that consists of a mixture of driving modes. United States, Australia, Canada, Sweden and Switzerland used this philosophy while devising their driving cycles.

4. Development of Real Drive Emission Tests and Cycle

Though stricter emission norms for automobiles have been introduced to improve the ambient air quality, the desired improvement has not been achieved, which can be attributed to the differences between the legislative and real-world vehicle use [44]. As discussed previously, several factors, such as road and climate conditions, affect the vehicle performance and makes chassis dynamometer emission testing not a reliable source for real emission from vehicles [45][46]. Furthermore, chassis dynamometer tests do not account for actual street layout and driver behaviour. If there is a difference in altitude or temperature, it will have an impact on parameters such as oxygen content, air intake and air-fuel ratio of the engine and which will vary the vehicle real drive emission [47].
EU has mandated RDE norms or in-use compliance standards since September 2017 to minimise this difference [48][49]. This mandate required vehicle emissions to be measured on the road with a PEMS in addition to measurements taken during the driving cycles performed under controlled laboratory conditions on a chassis dynamometer. RDE emission limits are defined by multiplying the respective NEDC emission limit by a “conformity factor (CF)” for a given emission. During a real road drive, a vehicle may initially emit ‘CF’ times as much as it does when tested under laboratory conditions.
The RDE legislation, which was introduced within the Euro 6 regulation, has been developed in 4 packages [50]. The first RDE package that defined the RDE test procedure was ratified in May 2015. The second package, which defined the NOx CFs and their introduction dates, was adopted in October 2015. The third package adopted in December 2016 included a Particle Number (PN) CF and RDE cold-start emissions. The fourth and final package adopted in May 2018 dealt with ‘In-Service Conformity’ RDE testing and market surveillance and lowered the 2020 NOx CF error margin from 0.5 to 0.43. NOx CF was mandated at 2.1 beginning in September 2017 (phase 1 of RDE) for new models and increasing to 2.1 beginning in September 2019 for all new vehicles. This factor was required to be 1.5 for new models beginning in January 2020 (phase 2 of RDE) and all new vehicles beginning in January 2021. A PN CF of 1.5 was mandated for new models beginning in September 2017 and for all new vehicles beginning in September 2018. Table 1 shows the TA tests and real operating conditions requirements for passenger vehicles between 2015 and 2022.
Table 1. Requirements for TA tests and real operating conditions for passenger vehicles in 2015–2022.
2015 2016 2017 2018 2019 2020 2021 2022
Euro 6b Euro 6c Euro 6d
Development & Measurement Phase Conformity Factor (CF)
CFNOx = 2.1, CFPN = 1.5 CFNOx, PN = 1.5
RDE for CO, NOX, PN emissions: EC 427/2016 and EC 646/2016 CO, NOX, PN and CO2
Commission Regulation (EU) 2016/427 outlines the primary trip conditions for an RDE cycle. This regulation determines the route’s characteristics (speeds, lengths, durations, and so on) as well as the ambient conditions. A concurrent regulation, Regulation 2016/646, includes criteria for trip dynamics as well as other specifications [51]. Table 2 presents the trip requirements for RDE.
Table 2. EU RDE route design specification (Regulation 2016/427).
  Unit Urban Rural Motorway Notes
Speed (V) km/h V ≤ 60 60 < V 90 ≤ V ≤ 145 V > 100 for at least 5 min in motorway
Distance % of total distance 29–44 33 ± 10 33 ± 10  
Minimum distance km 16 16 16  
Avg speed (Vavg) km/h 15 ≤ Vavg ≤ 40 - -  
Number of stops s several > 10 - -  
Max speed km/h 60 90 145  
Total test time min 90 to 120      
Elevating difference m 100     Between the start and endpoint
Some factors to consider while developing an RDE route [52]:
  • Urban driving must be achieved on routes with a maximum speed limit of 60 km/h.
  • If the urban driving segment includes any road with a speed limit greater than 60 km/h for any reason, the vehicle speed shall not exceed 60 km/h.
  • Roads with speed limits lower than the classification can exist in rural and freeway sections.
  • The road must be built such that the urban segment is travelled first, then the rural, and eventually the highway sections (using a topographical map).
  • It is necessary to operate the vehicle above 100 km/h (measured by the GPS) at least for 5 min.
  • The car must be capable of travelling at speeds ranging between 90 to 110 km/h.
There might be country-specific additional RDE criteria. For example, According to the “Pollutant Emission Limits and Measurement Methods of Light Vehicles (China phase 6)” standard, the proportions of urban, rural and highway are 34, 33 and 33%, respectively [53]. However, it is not always possible to fulfil all the criteria and develop a satisfactory RDE route.
In general, drive cycle development phases include three main components: test route discovery, data collection, and cycle design methods [54]. Route selection is an important aspect of the cycle development process where considerations are given on travel activity patterns as well as traffic flow characteristics. The data collection should consider driving both weekends and weekdays so that collected data represent different driving conditions based on the selected routes. Cycle construction is done by feeding driving data records into the representative cycle and then modifying and smoothing the cycle based on statistical analysis.

5. Real Drive Emission Cycle Tests

Yang et al. [55] evaluated diesel and gasoline vehicle real drive emissions. The authors developed an RDE route of 60 km consisting of urban, rural and motorways. The speed limit for the respective parts was 50, 90 and 130 km/h, which falls within the design specification. The vehicles were equipped with different emission reduction techniques. For emission measurement, a PEMS consisting of a Horiba OBS 2200 was used to collect unit to collect instantaneous and cumulative data of gaseous emissions (CO2, CO, THC, and NOx). The authors reported a higher gaseous emission for urban roads due to poor driving conditions and motorways due to excessive energy demand. CO and THC emission for all the vehicles were below the specific limit (for gasoline CO: 1.00 g/km and THC: 0.10 g/km, for diesel CO: 0.50 g/km and THC: 0.09 g/km). However, NOX emission was above the vehicle types’ limits (gasoline: 0.06 g/km, diesel: 0.08 g/km). Diesel vehicles emitted lower average trip CO2 compared to gasoline vehicles which might be associated with better thermal efficiency.
Thomas et al. [56] tested EURO V compliant gasoline vehicles fitted with a 3-way catalyst for emission reduction. The RDE tests were performed using PEMS devices: the Horiba OBS-ONE-GS PEMS equipment and the AVL MOVE Gas PEMSiS equipment. The trials started with urban driving, followed by rural and motorway driving sections. Urban, rural and motorway roads were approximately 34, 33 and 33% of the total route. RDE CO2 emissions were higher than the EU passenger car CO2 goal for 2015 (130 g/km). However, RDE CO emissions were 60% lower than the WLTC (well below the Euro 5 limit of 1 g/km), and RDE NOX emission was 34% lower compared to the WLTC emissions.
Wang et al. [57] evaluated volatile organic compounds emission from 4 different vehicles, including gasoline cars, light-duty diesel trucks, heavy-duty diesel trucks, and LPG-electric hybrid buses. The authors used two routes. Route A was approximately 68 km, including urban, suburban and highway roads, while route B was 18 km long route of No. B12 bus in Zhengzhou, China, which includes 29 stations. To simulate passengers dropping off and getting on, the bus was stopped at each station for 10 s. A SEMTECH ECOSTAR PLUS with an extra VOC sampling unit comprising three units: micro proportional sampling system (MPS), gas analyser, particulate matter (PM) analyser was used to measure emissions. The VOC emissions were different for different vehicles. The major VOC species for vehicles were as following:
  • Gasoline cars: i-pentane, acetone, propane, and toluene.
  • Light-duty diesel truck: mainly long-chain alkanes- dodecane, n-undecane, naphthalene and n-decane, which in total contributes to 70.4% of total species
  • Heavy-duty diesel truck: naphthalene contributed 31.8% of total VOC, which might be due to the engine operating conditions and the pyrolysation from incomplete combustion (Lin et al., 2019a, 2019b).
  • LPG bus: short-chain hydrocarbons, acetone, i-pentane, i-butane, n-butane and propane (46.7% of the total VOCs).
For the gasoline cars, aromatics take up 39.4, 35 and 41.7% of the tailpipe VOCs under the urban, suburban and highway conditions, respectively. The higher aromatic emission at the highway may be caused by the lower air/oil ratio of port fuel injection (PFI) under ultra-high-speed working conditions. Heavy-duty diesel trucks emitted 8.6 times higher VOC than light-duty diesel trucks, which can be attributed to poor vehicle maintenance as exhibited by the inefficient Selective Catalytic Reduction (SCR) device. Gasoline and LPG vehicles produced relatively lower VOC emissions compared to diesel vehicles. This could be attributed to the TWC of gasoline vehicles which might have reduced the VOC emissions. Highway operating conditions emitted much lower VOC emissions compared to urban road conditions.
Du et al. [58] tested the effect of cold-start on primary emission parameters. For the experiment, light-duty gasoline vehicles were selected, which were equipped with a TWC converter, closed-loop control of fuel injection and gasoline particle filter (GPF). The PEMS used in the tests was a HORIBA OBS-ONE. A route of 75.4 km was selected, which consisted of an urban section (32.6%), a rural one (32.4%) and a motorway section (35.0%). The altitude of the route ranged from 192.7–313.2 m, which satisfies the RDE test regulations requirements. The authors reported a significant increase in CO, CO2 and PN emission at the cold-start compared to a hot start.
Habib [59] studied three vehicles of varying age groups (BS-II/post- 2000; BS-III/post-2005, and BS-IV/post-2010). The fuels used in the vehicles were also different: gasoline, compressed natural gas (CNG) and diesel. The author selected a route of 10 km consisted of heavy traffic, lean traffic and traffic signals. On-road emissions were measured using Aerosol Emission Measurement System (AEMS), which consists of heated duct, dilution tunnel, zero air assembly, heated particle sampling probe and power supply unit. The author reported that diesel emitted the lowest CO, where gasoline emitted the highest. CO2 of gasoline vehicles were dependent upon acceleration and deceleration. Furthermore, the gasoline vehicle emitted a higher amount NOX of compared to the other two vehicles.
Cao et al. [60] also evaluated on-road VOC emission; however, they opted for a car chase method. The emission measurement system included an exhaust flow meter tube, mobile emission analyser, micro proportional sample system and VOC sampling unit. The test route included arterial roads (19.5 km) and highway roads (14.2 km). The route was divided into three defined driving cycles: arterial road hot start (ARHS), highway hot running (HWHR) and arterial road hot running (ARHR). The test vehicles were light-duty gasoline conformed to diverse emissions standards (Pre-China I to China IV). The authors reported that, for most of the vehicles, hot start resulted in the highest VOC emission, and highway hot running produced the lowest emission, which can be attributed to the low average speed and the effect of the hot start.
Daham et al. [61] investigated the impact of micro-scale driving actions (left and right turns, stops and start at traffic lights, etc.) on on-road vehicle emissions. The authors selected a route of 0.6 km, which consisted of four left-hand turns. They used several manual vehicles which conformed to Euro I to IV. They evaluated several driving variations, left turn (anticlockwise) with and without a stop at intersections; right turn (clockwise) with and without a stop at crossroads. The HC emission for the tests was well below the corresponding legislation. However, the NOx emission for all the vehicles were all above the legislative limits. The authors reported that aggressive driving behaviour heavily affects NOX and CO emission; a three times increase was observed. Aggressive driving also increased CO2 emissions significantly.
Roso and Martins [62] compared two different methods to develop an RDE cycle: average method and cumulative method. The emissions were evaluated using computational models developed through GT-Suite software. The authors used two vehicles to develop the cycle: bus and passenger vehicle and reported a significant increase of emission for cumulative methods compared to the FTP-75 cycle.
Zhou et al. [47] evaluated the effect of various environmental constraints on real drive NOX emission. If there is a difference in altitude or temperature, it will have an impact on parameters such as oxygen content, air intake and air-fuel ratio of the engine and which will vary in-cylinder combustion, amount of pollutants and fuel consumption of vehicles. Emission varies with temperature and speed. For example, with vehicle speed <20 km/h, low altitude NOX emission is higher than that of moderate altitude. High temperature and oxygen enrichment result in reduced NOX emission, and thus high altitude produces a lower emission. Akard et al. [63] also reported the influence of altitude on CO2 emission. The authors reported that a change in altitude of 90 m might result in a change in CO2 emission by 10 gm/mile.
Ren et al. [64] evaluated the effect of various alternative fuels on the emission of buses on their usual daily route. The fuels considered were diesel, 20% Waste cooking biodiesel+ 80% diesel (B20) and liquid natural gas (LNG). The PEMS was composed of a gas test unit: an onboard emissions measurement system and a particle test unit: engine exhaust particle sizer. Compared to diesel-operated buses, B20 and LNG buses had a reduction in PM emissions; however, NOx and PN emissions were higher.
Braisher et al. [65] evaluated on-road emission against legislative cycles such as NEDC, WLTC. The test cell is equipped with the Horiba MEXA-2000SPCS, and PN was measured using the pre-series instrument Nanomet3-PS where particle detection was based on aerosol particles corona charging. The selected driving route consists of an urban route (max speed of 50 km/h) and short segments (speed 70 km/h). The second route includes a long autobahn (high-speed road network) route with a max speed of 100 km/h. the complete PEMS evaluation run consists of two urban routes and one autobahn route. The total run time was approximately 90 min. Cold-start tests were conducted at different ambient temperatures (8 to 28 °C). The on-road measurements were performed using gasoline operated Euro-5 compliant passenger vehicle. The obtained results show that 60% of the trip PN emission is generated while the vehicle operates during the cold-start period. Braisher et al. [66] reported that during the NEDC cycle, 77% of the total PN emission is generated during the cold-start period. Furthermore, the tests also reveal that driving style is an essential parameter with a substantial impact on the PN emission. The autobahn trips show a significant change in PN emission (10× increase) when switched from normal to severe driving. This can be attributed to larger accelerations, higher velocities, and higher power demand.
Khalfan et al. [67] evaluated the effect of traffic congestion on vehicle emissions. A portable Fourier Transform Infrared (FTIR) spectrometer was used to measure real-world on-road emissions. The total route distance was 5 km, and the speed limit was 48 km/h. Two different cycles were conducted with varying numbers of right and left turns, traffic lights and pedestrian crossings. These dynamic factors would result in numerous stop/start events. The authors reported that congestion affected the CO2 emission; most of the trips produced more than 180 g/km CO2, which is above NEDC certification limits. THE CO and THC, and NOX emissions were dependent upon the traffic speed. These emissions were higher than the legislative limits at lower speeds.
Rosenblatt et al. [68] tested three variants of a motorbike on a 30 min test cycle, which consists of a cold-start phase, intermediate speed and high speed, with each stage being weighted equally at 0.33. The authors found that the PM emission was lower than the current Tier 3/LEV III light-duty highway vehicle limit of 3 mg/mile. A considerable fraction of CO and HC emissions were produced over the cold-start phase and/or high-speed phases, whereas NOX emission was most influential over the high-speed stage.
Modern-day vehicles have new technologies that help the driver, such as adaptive cruise control (ACC) and start-stop systems. ACC assists the driver in maintaining longitudinal control of their car when travelling on the highway, automatically adapting to different traffic situations. The system regulates the accelerator, engine powertrain, and vehicle brakes to maintain the desired time gap to the vehicle ahead. The start-stop system is a simple and low-cost solution in which the internal combustion engine is automatically turned off when the automobile is stopped and re-started at the driver’s request or as necessary. As a result, it avoids idle fuel use, such as that caused by traffic lights or congestion, which may account for up to 10% of overall consumption [69]. It is to be noted from the research of Warguła et al. [23] that a system similar to the start and stop system is only used in a machine (wood chipper), where idling occurred more frequently. This did not turn off the engine rather reduced its rotational speed, reducing fuel consumption [70], CO, CO2 and NOx emissions with increasing HC emission [23]. This confirms the fact that the internal combustion engine performs best under constant operating conditions. Limiting the idling fuel consumption as well as exhaust emission can be further achieved through cylinder deactivation [71]. This is also known as variable displacement engine technology. The method entails deactivating one or more cylinders by inhibiting valve actuation, causing the engine to run at a greater specific load across the remaining cylinders to provide the required torque [72][73]. Operating at such a position with a wider throttle opening decreases the engine’s pumping losses and, as a result, fuel consumption.
Dvorkin et al. [74] evaluated the effect of ACC on vehicle emissions on-road. The performance of ACC depends upon two factors: platooning and controlled acceleration. When vehicles closely follow each other to reduce aerodynamic drag, it is known as platooning, which is most effective in highway conditions where aerodynamic drag dictates road load forces. The author reported that active ACC resulted in less CO2 g/miles, and optimum GHG reduction is achieved when the following distance is 20–40 m and vehicles operating at highway speeds. In another study [75], the authors concluded that if households switched from conventional vehicles to electric vehicles, they could reduce their GHG emissions significantly.
Andersson et al. [76] evaluated two EURO 6 compliant light-duty diesel vehicles. These vehicles had two different technology installed to reduce NOX emission. One vehicle had SCR while the other had exhaust gas recirculation. Both consisted of diesel particulate filters for PM reduction. Furthermore, the vehicles were tested in two different routes, one with 60% urban condition and another with 60% motorway. The authors reported that both vehicles produced significantly higher NOX and CO2 emissions compared to the EURO 6 legislation limit; however, THC and CO emissions were within the limit.
Wang et al. [77] compared PEMS with a mobile monitoring system for on-road emissions. The authors selected heavy-duty diesel trucks that complied with China III to China V emission standards. The authors reported that the mobile monitoring system reported similar NOX results compared to that of the PEMS.
Park et al. [78] studied the on-road emission of 109 gasoline and diesel vehicles using PEMS on roads in Seoul (South Korea). The authors compared the emission results against laboratory experiment results and found that Euro 5 and Euro 6B standard vehicles emitted 5 times more on-road NOX compared to laboratory-based tests. The authors also reported that the on-road NOX emission is also dependent on factors such as driving dynamics and ambient temperature. One drawback of the study is that the stop ratio of more than 30%, which does not meet the EU RDE regulations. However, the average speed of the vehicles was within 15 to 40 km/h, which is within the regulations.
Bischoff et al. [79] compared the on-road emission of motorcycles. The authors evaluated two driving styles, normal and dynamic driving, where the latter represents a sporty driving style with increased longitudinal dynamics. The authors reported that CO and NOX emissions were 58 and 36% higher than that of WMTC certification limits. Furthermore, CO, CO2 and NOX emissions increased significantly when switched from normal driving to dynamic driving.
Table 6 presents a summary of RDE route descriptions and emission results from various literature.

6. Comparison of RDE and laboratory testing

Degraeuwe and Weiss [80] compared NOX emissions from on-road testing and laboratory-based NEDC tests for diesel and gasoline vehicles. According to the authors, the NOX emissions of diesel engines in laboratory tests are below the emission level limit, but on-road emissions are far above the limit. The on-road emissions from gasoline vehicles are higher than the NEDC pollution values, but they are still within the emission limits. On-road NOX emissions for diesel cars are 181 percent higher than the NEDC average. Several national form approval authorities confirmed that tested vehicles emit emissions below the limit in a laboratory setting, but 4.5 to 4.7 times higher than the limit for EURO 5 and EURO 6 vehicles [81][82]. In contrast to laboratory-based experiments, on-road tests released 50% more NOX, according to Pirjola et al. [83]. Valverde et al. [84] conducted on-road and in-laboratory NEDC studies on diesel and gasoline vehicles. On-road emissions for diesel vehicles were 14 times higher than NEDC tests and 6 times higher than type approval limits, according to the authors. The authors also stated that PN emissions for diesel cars were below the TA limit in both on-road and laboratory tests, and CO2 emissions for on-road were marginally higher than the TA limit. On-road and in-lab NOX emissions from gasoline vehicles were within the TA cap. On-road emissions and chassis dynamometer-based in-lab measurements were compared by Besch et al. [85]. The authors used two different routes with a Jeep Grand Cherokee and found that NOX emissions were significantly higher on both routes as compared to chassis dynamometer cycles. Park et al. [78] also reported that on-road NOX emission was five times higher than laboratory-based emission tests. On the contrary, Thomas et al. [56] reported 34% lower NOX emission and 60% lower CO emission compared to laboratory cycle-based emission results. The major factors for such discrepancies between on-road and laboratory-based emission findings are that on-road emissions are affected by various factors that are not considered in laboratory-based driving cycles, such as driver aggression, congestion, road gradient, etc. Furthermore, most authors indicated that NOX and PN emissions are the ones that differentiate from laboratory studies. 

7. Conclusion

In recent years researchers have found a significant difference in emissions reported using type emission tests and on-road emission tests. The test drive cycles employed to measure the emissions produced by vehicles are expected to adequately represent the vehicle's real-world driving pattern to provide the most realistic estimation of these levels. However, which is not the case. Furthermore, two recent scandals have identified that auto manufacturing companies use emission defeat devices that would reduce vehicle emission by tracking when used in chassis dynamometer and enabling emission reduction techniques. These have resulted in researchers prioritising on-road emission tests known as RDE testing. The paper discusses RDE development methods and reviews past works. The review shows that various factors such as traffic signal, driving dynamics, congestions, altitude, ambient temperature etc., have a significant impact on on-road emissions. In addition, driving behaviour, along with the driving route, significantly impacts vehicle emission, which is not represented in type emission tests. For example, aggressive driving behaviour increased NOx and CO emissions three times than normal driving behaviour. Route characteristics such as traffic lights, right/left turns, roundabouts, gradients were all found to have a significant impact on vehicle emissions. The literature review also indicated that modern vehicle technologies such as start-stop systems also affect vehicle emission. The start-stop system results in increased emission due to the engine not operating in conditions intended, i.e. stoichiometric operation and operating temperatures because of frequent stops and starts. This contributes to the disturbance of the mixture composition (enrichment during acceleration, idle when reducing the rotational speed). These factors cause the engine to work on mixtures other than stoichiometric, i.e. unfavourable from the point of view of exhaust emissions and exhaust after-treatment systems. This also corroborates the fact that an internal combustion engine performs best under constant operating conditions. The driving dynamics are not represented in the current laboratory-based test procedures. Thus, it is important to consider all these factors when developing a real drive emission cycle to evaluate the emission level of any vehicle. This, in turn, will significantly improve the air quality around the world.


  1. Mofijur, M.; Fattah, I.R.; Alam, A.; Islam, A.S.; Ong, H.C.; Rahman, S.A.; Najafi, G.; Ahmed, S.; Uddin, A.; Mahlia, T. Impact of COVID-19 on the social, economic, environmental and energy domains: Lessons learnt from a global pandemic. Sustain. Prod. Consum. 2021, 26, 343–359.
  2. International Energy Agency (IEA). Global Energy Review. 2021. Available online: (accessed on 1 July 2021).
  3. Ritchie, H.; Roser, M. Emissions by Sector. Available online: (accessed on 1 July 2021).
  4. Mengpin, G.; Johannes, F. 4 Charts Explain Greenhouse Gas Emissions by Countries and Sectors. Available online: (accessed on 1 July 2021).
  5. McGrath, M. Climate Change and Coronavirus: Five Charts about the Biggest Carbon Crash. Available online: (accessed on 24 September 2020).
  6. Johns Hopkins University (JHU). COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins Coronavirus Resource Center. Global Map. Available online: (accessed on 3 July 2021).
  7. Delphi Technologies. Current Emissions Standard Guides. Available online: (accessed on 24 September 2020).
  8. Al-Kindi, S.G.; Brook, R.D.; Biswal, S.; Rajagopalan, S. Environmental determinants of cardiovascular disease: Lessons learned from air pollution. Nat. Rev. Cardiol. 2020, 17, 656–672.
  9. Xie, J.; Teng, J.; Fan, Y.; Xie, R.; Shen, A. The short-term effects of air pollutants on hospitalizations for respiratory disease in Hefei, China. Int. J. Biometeorol. 2019, 63, 315–326.
  10. Van Mierlo, J.; Maggetto, G.; Van de Burgwal, E.; Gense, R. Driving style and traffic measures-influence on vehicle emissions and fuel consumption. Proc. Inst. Mech. Eng. Part D J. Automob. Eng. 2004, 218, 43–50.
  11. Perry, R.; Gee, I. Vehicle emissions in relation to fuel composition. Sci. Total Environ. 1995, 169, 149–156.
  12. Noland, R.B.; Quddus, M.A. Flow improvements and vehicle emissions: Effects of trip generation and emission control technology. Transp. Res. Part D Transp. Environ. 2006, 11, 1–14.
  13. Drozd, G.T.; Zhao, Y.; Saliba, G.; Frodin, B.; Maddox, C.; Weber, R.J.; Chang, M.-C.O.; Maldonado, H.; Sardar, S.; Robinson, A.L.; et al. Time Resolved Measurements of Speciated Tailpipe Emissions from Motor Vehicles: Trends with Emission Control Technology, Cold Start Effects, and Speciation. Environ. Sci. Technol. 2016, 50, 13592–13599.
  14. Franco, V.; Kousoulidou, M.; Muntean, M.; Ntziachristos, L.; Hausberger, S.; Dilara, P. Road vehicle emission factors development: A review. Atmos. Environ. 2013, 70, 84–97.
  15. Samuel, S.; Austin, L.; Morrey, D. Automotive test drive cycles for emission measurement and real-world emission levels-a review. Proc. Inst. Mech. Eng. Part D J. Automob. Eng. 2002, 216, 555–564.
  16. Kleeman, P. A fresh look at predicting carbon monoxide impacts at highway intersections. In Proceedings of the Transport Research Board A1 FC03-AIF06 Joint Summer Meeting, Ann Arbor, MI, USA, 11–15 January 1998.
  17. Varella, R.A.; Duarte, G.; Baptista, P.; Sousa, L.; Villafuerte, P.M. Comparison of Data Analysis Methods for European Real Driving Emissions Regulation. SAE Tech. Pap. Ser. 2017, 1, 997.
  18. Ashtari, A.; Bibeau, E.; Shahidinejad, S. Using Large Driving Record Samples and a Stochastic Approach for Real-World Driving Cycle Construction: Winnipeg Driving Cycle. Transp. Sci. 2014, 48, 170–183.
  19. Gong, Q.; Midlam-Mohler, S.; Marano, V.; Rizzoni, G. An Iterative Markov Chain Approach for Generating Vehicle Driving Cycles. SAE Int. J. Engines 2011, 4, 1035–1045.
  20. Nyberg, P.; Frisk, E.; Nielsen, L. Driving Cycle Equivalence and Transformation. IEEE Trans. Veh. Technol. 2017, 66, 1963–1974.
  21. Merkisz, J.; Pielecha, J. Comparison of Real Driving Emissions tests. IOP Conf. Ser. Mater. Sci. Eng. 2018, 421, 042055.
  22. Kamińska, M.; Rymaniak, Ł.; Lijewski, P.; Szymlet, N.; Daszkiewicz, P.; Grzeszczyk, R. Investigations of Exhaust Emissions from Rail Machinery during Track Maintenance Operations. Energies 2021, 14, 3141.
  23. Warguła, Ł.; Kukla, M.; Lijewski, P.; Dobrzyński, M.; Markiewicz, F. Influence of Innovative Woodchipper Speed Control Systems on Exhaust Gas Emissions and Fuel Consumption in Urban Areas. Energies 2020, 13, 3330.
  24. Waluś, K.J.; Warguła, Ł.; Krawiec, P.; Adamiec, J.M. Legal regulations of restrictions of air pollution made by non-road mobile machinery—The case study for Europe: A review. Environ. Sci. Pollut. Res. 2018, 25, 3243–3259.
  25. Rymaniak, Ł.; Lijewski, P.; Kamińska, M.; Fuć, P.; Kurc, B.; Siedlecki, M.; Kalociński, T.; Jagielski, A. The role of real power output from farm tractor engines in determining their environmental performance in actual operating conditions. Comput. Electron. Agric. 2020, 173, 105405.
  26. Warguła, Ł.; Kukla, M.; Lijewski, P.; Dobrzyński, M.; Markiewicz, F. Impact of Compressed Natural Gas (CNG) Fuel Systems in Small Engine Wood Chippers on Exhaust Emissions and Fuel Consumption. Energies 2020, 13, 6709.
  27. Warguła, Ł.; Kukla, M.; Lijewski, P.; Dobrzyński, M.; Markiewicz, F. Influence of the Use of Liquefied Petroleum Gas (LPG) Systems in Woodchippers Powered by Small Engines on Exhaust Emissions and Operating Costs. Energies 2020, 13, 5773.
  28. Mahlia, T.M.I.; Tohno, S.; Tezuka, T. A review on fuel economy test procedure for automobiles: Implementation possibilities in Malaysia and lessons for other countries. Renew. Sustain. Energy Rev. 2012, 16, 4029–4046.
  29. Hooftman, N.; Messagie, M.; Van Mierlo, J.; Coosemans, T. A review of the European passenger car regulations—Real driving emissions vs local air quality. Renew. Sustain. Energy Rev. 2018, 86, 1–21.
  30. Agarwal, A.K.; Mustafi, N.N. Real-world automotive emissions: Monitoring methodologies, and control measures. Renew. Sustain. Energy Rev. 2021, 137, 110624.
  31. Graham, L.A.; Rideout, G.; Rosenblatt, D.; Hendren, J. Greenhouse gas emissions from heavy-duty vehicles. Atmos. Environ. 2008, 42, 4665–4681.
  32. Ashraful, A.M.; Masjuki, H.H.; Kalam, M.A.; Fattah, I.M.R.; Imtenan, S.; Shahir, S.A.; Mobarak, H.M. Production and comparison of fuel properties, engine performance, and emission characteristics of biodiesel from various non-edible vegetable oils: A review. Energy Convers. Manag. 2014, 80, 202–228.
  33. Fattah, I.R.; Masjuki, H.; Liaquat, A.; Ramli, R.; Kalam, A.; Riazuddin, V. Impact of various biodiesel fuels obtained from edible and non-edible oils on engine exhaust gas and noise emissions. Renew. Sustain. Energy Rev. 2013, 18, 552–567.
  34. Giakoumis, E.G. Driving and Engine Cycles; Springer Science and Business Media LLC: Cham, Switzerland, 2017.
  35. Tzirakis, E.; Pitsas, K.; Zannikos, F.; Stournas, S. Vehicle emissions and driving cycles: Comparison of the Athens Driving Cycle (ADC) with ECE-15 and European Driving Cycle (EDC). Glob. NEST J. 2006, 8, 282–290.
  36. Lyons, T.; Kenworthy, J.; Austin, P.; Newman, P. The development of a driving cycle for fuel consumption and emissions evaluation. Transp. Res. Part A Gen. 1986, 20, 447–462.
  37. Kühler, M.; Karstens, D. Improved Driving Cycle for Testing Automotive Exhaust Emissions. SAE Tech. Pap. Ser. 1978.
  38. Tong, H.; Hung, W.; Cheung, C. Development of a driving cycle for Hong Kong. Atmos. Environ. 1999, 33, 2323–2335.
  39. Giakoumis, E.; Rakopoulos, C.; Dimaratos, A.M.; Rakopoulos, D.C. Exhaust emissions with ethanol or n-butanol diesel fuel blends during transient operation: A review. Renew. Sustain. Energy Rev. 2013, 17, 170–190.
  40. Andreae, M.; Salemme, G.; Kumar, M.; Sun, Z. Emissions Certification Vehicle Cycles Based on Heavy Duty Engine Test Cycles. SAE Int. J. Commer. Veh. 2012, 5, 299–309.
  41. Watson, H.; Milkins, E.; Braunsteins, J. Development of the Melbourne peak cycle. In Proceedings of the Second Conference on Traffic Energy and Emissions, Melbourne, Australia, 19–21 May 1982.
  42. Metwalley, S.M.; Abouel-Seoud, S.; Farahat, A.M. Determination of the catalytic converter performance of bi-fuel vehicle. J. Pet. Technol. Altern. Fuels 2011, 2, 111–131.
  43. Bullock, K.J. Driving cycles. In Proceedings of the Second Conference on Traffic, Energy and Emissions, Melbourne, Australia, 19–21 May 1982; pp. 1–18.
  44. Duarte, G.; Gonçalves, G.; Farias, T. Analysis of fuel consumption and pollutant emissions of regulated and alternative driving cycles based on real-world measurements. Transp. Res. Part D Transp. Environ. 2016, 44, 43–54.
  45. Pang, Y.; Fuentes, M.; Rieger, P. Trends in the emissions of Volatile Organic Compounds (VOCs) from light-duty gasoline vehicles tested on chassis dynamometers in Southern California. Atmos. Environ. 2014, 83, 127–135.
  46. Chen, L.; Wang, Z.; Liu, S.; Qu, L. Using a chassis dynamometer to determine the influencing factors for the emissions of Euro VI vehicles. Transp. Res. Part D Transp. Environ. 2018, 65, 564–573.
  47. Zhou, H.; Zhao, H.; Feng, Q.; Yin, Z.; Li, J.; Qin, K.; Li, M.; Cao, L. Effects of environmental parameters on real-world nox emissions and fuel consumption for heavy-duty diesel trucks using an OBD approach; 0148-7191. SAE Tech. Pap. 2018, 1, 1817.
  48. Betageri, V.; Mahesh, R. Effects of the Real Driving Conditions on the NOx Emission of a Medium Duty Diesel Commercial Vehicle. SAE Tech. Pap. Ser. 2017.
  49. Bodisco, T.; Zare, A. Practicalities and Driving Dynamics of a Real Driving Emissions (RDE) Euro 6 Regulation Homologation Test. Energies 2019, 12, 2306.
  50. The Association for Emissions Control by Catalyst (AECC). Real Driving Emissions. Available online: (accessed on 5 February 2021).
  51. Donateo, T.; Giovinazzi, M. Building a cycle for Real Driving Emissions. Energy Procedia 2017, 126, 891–898.
  52. Roberts, P.J.; Mumby, R.; Mason, A.; Redford-Knight, L.; Kaur, P. RDE Plus—The Development of a Road, Rig and Engine-in-the-Loop Test Methodology for Real Driving Emissions Compliance. SAE Tech. Pap. Ser. 2019.
  53. Zhang, Y.; Tian, D.; Du, H.; Pan, H.; Fang, W.; Wang, Y. Design and Research of RDE Test Routes. In Advances in Intelligent Systems and Computing; Springer Science and Business Media LLC: Cham, Switzerland, 2019; pp. 1160–1169.
  54. Tong, H.; Tung, H.; Hung, W.-T.; Nguyen, H. Development of driving cycles for motorcycles and light-duty vehicles in Vietnam. Atmos. Environ. 2011, 45, 5191–5199.
  55. Yang, Z.; Liu, Y.; Wu, L.; Martinet, S.; Zhang, Y.; Andre, M.; Mao, H. Real-world gaseous emission characteristics of Euro 6b light-duty gasoline- and diesel-fueled vehicles. Transp. Res. Part D Transp. Environ. 2020, 78, 102215.
  56. Thomas, D.; Li, H.; Wang, X.; Song, B.; Ge, Y.; Yu, W.; Ropkins, K. A Comparison of Tailpipe Gaseous Emissions for RDE and WLTC Using SI Passenger Cars. SAE Tech. Pap. Ser. 2017, 1.
  57. Wang, M.; Li, S.; Zhu, R.; Zhang, R.; Zu, L.; Wang, Y.; Bao, X. On-road tailpipe emission characteristics and ozone formation potentials of VOCs from gasoline, diesel and liquefied petroleum gas fueled vehicles. Atmos. Environ. 2020, 223, 117294.
  58. Du, B.; Zhang, L.; Geng, Y.; Zhang, Y.; Xu, H.; Xiang, G. Testing and evaluation of cold-start emissions in a real driving emissions test. Transp. Res. Part D Transp. Environ. 2020, 86, 102447.
  59. Jaiprakash; Habib, G. On-road assessment of light duty vehicles in Delhi city: Emission factors of CO, CO2 and NOX. Atmos. Environ. 2018, 174, 132–139.
  60. Cao, X.; Yao, Z.; Shen, X.; Ye, Y.; Jiang, X. On-road emission characteristics of VOCs from light-duty gasoline vehicles in Beijing, China. Atmos. Environ. 2016, 124, 146–155.
  61. Daham, B.; Li, H.; Andrews, G.E.; Ropkins, K.; Tate, J.E.; Bell, M. Comparison of Real World Emissions in Urban Driving for Euro 1-4 Vehicles Using a PEMS. SAE Tech. Pap. Ser. 2009.
  62. Roso, V.; Martins, M.E.S. Simulation of Fuel Consumption and Emissions for Passenger Cars and Urban Buses in Real-World Driving Cycles. SAE Tech. Pap. Ser. 2016, 1.
  63. Akard, M.; Gramlich, N.; Nevius, T.; Porter, S. Comparison of Real-World Urban Driving Route PEMS Fuel Economy with Chassis Dynamometer CVS Results. SAE Tech. Pap. Ser. 2019.
  64. Ren, Y.; Lou, D.; Zhang, Y.; Tan, P.; Hu, Z. Study on Real-World NOx and Particle Emissions of Bus: Influences of VSP and Fuel. SAE Tech. Pap. Ser. 2019.
  65. Gallus, J.; Kirchner, U.; Vogt, R.; Börensen, C.; Benter, T. On-road particle number measurements using a portable emission measurement system (PEMS). Atmos. Environ. 2016, 124, 37–45.
  66. Braisher, M.; Stone, R.; Price, P. Particle Number Emissions from a Range of European Vehicles. SAE Tech. Pap. Ser. 2010.
  67. Khalfan, A.; Andrews, G.; Li, H. Real World Driving: Emissions in Highly Congested Traffic. SAE Tech. Pap. Ser. 2017, 1.
  68. Rosenblatt, D.; Stokes, J.; Caffrey, C.; Brown, K.F. Effect of Driving Cycles on Emissions from On-Road Motorcycles. SAE Tech. Pap. Ser. 2020.
  69. Fonseca, N.; Casanova, J.; Valdés, M. Influence of the stop/start system on CO2 emissions of a diesel vehicle in urban traffic. Transp. Res. Part D Transp. Environ. 2011, 16, 194–200.
  70. Warguła, Ł.; Krawiec, P.; Waluś, K.J.; Kukla, M. Fuel Consumption Test Results for a Self-Adaptive, Maintenance-Free Wood Chipper Drive Control System. Appl. Sci. 2020, 10, 2727.
  71. Zsiga, N.; Ritzmann, J.; Soltic, P. Practical Aspects of Cylinder Deactivation and Reactivation. Energies 2021, 14, 2540.
  72. Parker, M.C.; Jiang, C.; Butcher, D.; Spencer, A.; Garner, C.P.; Witt, D. Impact and observations of cylinder deactivation and reactivation in a downsized gasoline turbocharged direct injection engine. Int. J. Engine Res. 2021, 22, 1367–1376.
  73. Savickas, D.; Steponavičius, D.; Domeika, R. Analysis of Telematics Data of Combine Harvesters and Evaluation of Potential to Reduce Environmental Pollution. Atmosphere 2021, 12, 674.
  74. Dvorkin, W.; King, J.; Gray, M.; Jao, S. Determining the Greenhouse Gas Emissions Benefit of an Adaptive Cruise Control System Using Real-World Driving Data. SAE Tech. Pap. Ser. 2019.
  75. Laberteaux, K.; Hamza, K. A Study of Greenhouse Gas Emissions Reduction Opportunity in Light-Duty Vehicles by Analyzing Real Driving Patterns. SAE Tech. Pap. Ser. 2017, 1.
  76. Andersson, J.; May, J.; Favre, C.; Bosteels, D.; De Vries, S.; Heaney, M.; Keenan, M.; Mansell, J. On-Road and Chassis Dynamometer Evaluations of Emissions from Two Euro 6 Diesel Vehicles. SAE Int. J. Fuels Lubr. 2014, 7, 919–934.
  77. Wang, H.; Wu, Y.; Zhang, K.M.; Zhang, S.; Baldauf, R.W.; Snow, R.; Deshmukh, P.; Zheng, X.; He, L.; Hao, J. Evaluating mobile monitoring of on-road emission factors by comparing concurrent PEMS measurements. Sci. Total Environ. 2020, 736, 139507.
  78. Park, J.; Shin, M.; Lee, J.; Lee, J. Estimating the effectiveness of vehicle emission regulations for reducing NOx from light-duty vehicles in Korea using on-road measurements. Sci. Total Environ. 2021, 767, 144250.
  79. Bischoff, G.; Keller, S.; Heubuch, A. Portable Emission Measurement Technology and RDE on Motorcycles as Instruments for Future Challenges. MTZ Worldw. 2020, 81, 54–59.
  80. Degraeuwe, B.; Weiss, M. Does the New European Driving Cycle (NEDC) really fail to capture the NOX emissions of diesel cars in Europe? Environ. Pollut. 2017, 222, 234–241.
  81. Mathews, L.T.; Neti, R.M. Vehicle Emissions Testing System. Google Patents 5,753,185, 19 May 1998.
  82. BMVI (Bundesministerium Für Verkehr und Digitale Infrastruktur). Bericht der Untersuchungskommission Volkswagen. Available online: (accessed on 1 July 2021).
  83. Pirjola, L.; Rönkkö, T.; Saukko, E.; Parviainen, H.; Malinen, A.; Alanen, J.; Saveljeff, H. Exhaust emissions of non-road mobile machine: Real-world and laboratory studies with diesel and HVO fuels. Fuel 2017, 202, 154–164.
  84. Valverde, V.; Mora, B.; Clairotte, M.; Pavlovic, J.; Suarez-Bertoa, R.; Giechaskiel, B.; Astorga-Llorens, C.; Fontaras, G. Emission Factors Derived from 13 Euro 6b Light-Duty Vehicles Based on Laboratory and On-Road Measurements. Atmosphere 2019, 10, 243.
  85. Besch, M.C.; Chalagalla, S.H.; Carder, D. On-Road and Chassis Dynamometer Testing of Light-duty Diesel Passenger Cars. Available online: (accessed on 1 July 2021).
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