Surveys and Fuel Consumption Measurement Provide Data for Analysis of Fuel Consumption Factors: Since the initial introduction of hybrid trucks in Japan, their number had increased to 5,600 units as of March 2008. Fuel economy improvement achieved by these hybrid trucks varies significantly, however. Thus, researchers the study group called The Promotion of Low-Emission Vehicles conducted a government-sponsored project to investigate the fuel economy of a commercial hybrid truck having the gross vehicle weight of 2 tons. This chapter reports the survey method as well as the results and discussion of the data scatter and the test results.