 His first full car design was for the Auto Union Type D Grand Prix car.With a swept volume of three litres, in accordance with the contemporary Grand Prix regulations, the supercharged V12 rear-mounted engine could develop and provided Grand Prix victories for Tazio Nuvolari and Hermann Paul Müller.Eberan-Eberhorst was heavily involved in the initial testing of each new racing car, developing an on-board recording instrument to plot parameters such as car speed, engine speed, gear change and braking points.