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Τhis study demonstrates the combination of a microscopic traffic simulator (AIMSUN) with an instantaneous emissions model (AVL CRUISE) to investigate the impact of traffic congestion on fuel consumption on an urban arterial road. The micro traffic model was enhanced by an improved car-following law according to Morello et al. (2014) and was calibrated to replicate measured driving patterns over an urban corridor in Turin, Italy, operating under adaptive urban traffic control (UTC). The method was implemented to study the impact of congestion on fuel consumption for the category of Euro 5 diesel

The paper presents the results of the effect of various fuel economy technologies on the certified CO 2 emissions of light duty vehicles. The vehicles operate under two different driving cycles, namely the New European Driving Cycle (NEDC) and the Worldwide harmonized Light duty Test Procedure (WLTP), which is considered closer to real world driving and is going to be the new type approval test in the near future. The study focuses on the comparative evaluation of the effect of each technology on CO 2 emissions under these two driving cycles. To this aim, simulation models for a number of passenger cars were developed and validated against test data, generated via a specifically developed test protocol. In order to cover a large share of the market, the European fleet was divided into a number of segments based on specific vehicle characteristics and technologies, and representative vehicles for each segment were chosen. In order to minimize flexibilities and sources of uncertainty, the models were developed according to a standardized modelling procedure, based on the development of a reference “template model”. AVL's Cruise was used as simulation platform. The various components and modules for each vehicle model, as well as the respective input parameters, were defined with the support of the respective OEMs. After gaining confidence in the simulation models for all the vehicles considered in the present work, additional technologies, such as start-stop, brake energy recuperation and different drivetrain configurations, were implemented in each model. Specific strategies have been defined for the implementation of individual technologies and, where needed, additional algorithms were developed in Cruise. The results show that the effect of each technology on CO 2 emissions is different between NEDC and WLTP, owing to the different characteristics of each cycle. For example, the effect of start-stop on CO 2 emissions is larger in NEDC, due to longer idling periods compared to WLTP. In this context, the results of this study can provide useful indications for the most effective fuel economy technologies under the new type approval procedure.

In-use fuel consumption data of 924 passenger cars (611 petrol, 313 diesel) were collected from various European sources and were evaluated in comparison to their corresponding type-approval values. The analysis indicated that the average in-use fuel consumption was higher than the type-approval one by 11% for petrol cars and 16% for diesel cars. Comparison of this dataset with the Travelcard database in the Netherlands showed that the deviation increased for late model years and in particular for cars with low type-approval values. The deviation was higher than 60% for vehicles registered in 2012 within the 90–100 gCO 2 /km bin. Unrealistic vehicle resistances used in type-approval were identified as one of the prime reasons of the difference. A simplified linear model developed in the study may be used to predict in-use fuel consumption based on data publicly available. The model utilizes the fuel consumption measured in type-approval, the mass, and the engine capacity to provide in-use fuel consumption. This may be either used to correct fuel consumption factors currently utilized by emission models (e.g. COPERT, HBEFA, VERSIT+, and others) or could be used independently to make projections on how fuel consumption may develop on the basis of changing future passenger cars characteristics.

In 2014 the United Nations Economic Commission for Europe (UNECE) adopted the global technical regulation No. 15 concerning the Worldwide harmonized Light duty Test Procedure (WLTP). Having significantly contributed to its development, the European Commission is now aiming at introducing the new test procedure in the European type-approval legislation for light duty vehicles in order to replace the New European Driving Cycle (NEDC) as the certification test. The current paper aims to assess the effect of WLTP introduction on the reported CO 2 emissions from passenger cars presently measured under the New European Driving Cycle and the corresponding test protocol. The most important differences between the two testing procedures, apart from the kinematic characteristics of the respective driving cycles, is the determination of the vehicle inertia and driving resistance, the gear shifting sequence, the soak and test temperature and the post-test charge balance correction applied to WLTP. In order to quantify and analyze the effect of these differences in the end value of CO 2 emissions, WLTP and NEDC CO 2 emission measurements were performed on 20 vehicles, covering almost the whole European market. WLTP CO 2 values range from 125.5 to 217.9 g/km, NEDC values range from 105.4 to 213.2 g/km and the ΔCO 2 between WLTP and NEDC ranges from 4.7 to 29.2 g/km for the given vehicle sample. The average cold start effect over WLTP was found 6.1 g/km, while for NEDC it was found 12.3 g/km. For a small gasoline and a medium sized diesel passenger car, the different inertia mass and driving resistance is responsible 63% and 81% of the observed ΔCO 2 between these two driving cycles respectively, whereas the other parameters (driving profile, gear shifting, test temperature) account for the remaining 37% and 19%.