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.