China is experiencing rapid motorization and each city has a unique motorization pathway owing to its different characteristics and development progress. The temporal and spatial variation trend in on-road energy use and CO2 emissions need to be better understood in order to project the future growth and to support policy-making at both local and national levels. This study simulates the on-road energy use and CO2 emissions of all of China's prefectural-level cities (and above) from 1978 through 2008, on the basis of the collected vehicle data from hundreds of national and local statistical yearbooks. The results show that China's on-road energy use and CO2 emissions were 119 million metric tons (MMT) and 377 MMT in 2008, respectively-20 times the levels in 1978. The economically developed cities and heavy industrial cities had the highest on-road energy use and CO2 emissions before the year 2000, but recently the spatial distribution has varied significantly as the uptake of motorization increases successively in these cities. Now and in the near future, the most important driving force of the on-road energy and CO2 growth in China is the great number of average cities that have just started or will soon start the motorization. (C) 2013 Elsevier Ltd. All rights reserved.