Abstract
A brief description is given of the theoretical aspects as well as the practical application of roof spoilers and wind deflectors on tractor trailer combinations in order to reduce the fuel consumption of the vehicle. Field tests were made with a Model 1624S Mercedes-Benz tractor with trailer vehicle on which the roof spoiler and wind deflectors are mounted respectively on tractor and trailer. Measurements during the tests indicate that the aerodynamic drag of the vehicle combination decreases with 20% which in turn results in 6% less fuel consumption.