Sugar Beet Harvesters belong to self-propelled agricultural machinery for trimming, lifting, cleaning and collecting sugar beets. Like most harvesting machines such vehicles are equipped with hydrostatic traction drives to ensure a continuous variable speed adjustment for the harvesting process. These drives are state of the art but rather moderate in efficiency. For further enhancement of effi- ciency the hydrostatic system was replaced by a diesel-electric traction drive. The two different systems were tested and compared in simula- tion and field. As a result, improved driving performance at reduced fuel consumption could be achieved.