White paper

Evaluation of real-world fuel consumption of light-duty vehicles in China

There is growing evidence globally and in China of the gap between laboratory test findings and real-world carbon dioxide (CO2) emissions and fuel consumption. Building on previous work, this project uses different sources of real-world CO2 emissions and fuel consumption data for light-duty vehicles (LDVs) to analyze real-world patterns in support of regulatory program development.

The study starts with an updated summary of consumer experience data that are representative of fleet trends. Then, new analyses are conducted using detailed vehicle fuel consumption data collected from two testing measures – real-world testing with portable emission measurement systems (PEMS) and chassis dynamometer tests in the laboratory.

Analyzing different data sources, this study reaches four findings:

Finding 1: The increasing gap between real-world and type-approval fuel consumption will dilute the practical effects of consumption policies.

Finding 2: The mismatch between real-world and type-approval fuel consumption will reduce consumers’ faith in data on labels and government certification.

Finding 3: Different driving conditions including road load, driving cycle, and A/C application significantly influence the test results for CO2 emissions and fuel consumption.

Finding 4: Although the WLTP covers a wider range of driving conditions than the NEDC, the RDE test better represents actual on-road driving behaviors.

official vs consumer reported fuel efficiency


estimated co2 emissions