Carbon dioxide emissions and fuel consumption from passenger cars tested over the NEDC and WLTC – an overview and experimental results from market-representative vehicles

EU legislation specifies that the New European Driving Cycle (NEDC) be used for type approval testing of existing (not new) types of passenger cars, a test which generates official values for CO₂ emissions and fuel consumption (which is calculated from CO₂ emissions based on a carbon balance). A significant body of evidence shows that the type approval values obtained by manufacturers of light duty vehicles are lower than those which occur during real usage on the road. Longstanding objections that the current test cycle is unrepresentative and delivers unrealistic results has led to the development of a worldwide harmonized light-duty test cycle (WLTC), as part of wider changes in the overall test procedure (the worldwide harmonized light-duty test procedure – WLTP). This paper discusses both driving cycles and their characteristics with the aim of making the topic accessible to the non-specialist; later in the paper CO₂ and fuel consumption results obtained by testing several European passenger cars over both cycles in an emissions testing laboratory are reported. The test vehicles were a good representation of passengers cars in use in EU countries such as Poland – they featured both spark ignition and compression ignition engines, met the Euro 5 standard and had appreciable accumulated mileages.