It is difficult to obtain accurate fuel consumption data for privately owned in-use vehicles. This study aims to directly measure fuel consumption and the various parameters which affect fuel consumption from in-use vehicles via various methods. Motorcycle power demands were determined from measured frontal area, vehicle mass, rider and payload mass, tire pressure. Both worst case and best case scenarios of load, tire pressure and frontal area were measured for aerodynamic and rolling resistance via the roll-down technique. Measured data points for typical motorcycles fall within the established best- and worst-case scenarios, and an “average case” is selected for vehicle testing. Several common motorcycles models are tested for their fuel consumption at the established “average load” case. Additionally, this typical load case is coupled with the ECER40 drive cycle pattern for estimates of field fuel consumption from chassis dynamometer testing. The dynamometer fuel consumption measurements agree well with in-use vehicle fuel consumption measurements. Results are further analyzed in terms of motorcycle make, engine size and technology indicating a large disparity between functionally identical motorcycles and the economic impact of 2-stroke versus 4-stroke fuel consumption.