It's a Scheuch-Schlepper (tractor), originally intended for agricultural use. The Scheuch company of Erfurt developed it in co-operation with Auto-Union, and various DKW engines were used. The wheel track could be varied to make it fit in different furrows. It could be used as a three-wheeled tractor, or the rear wheel could be detached by releasing four bolts, after which agricultural equipment could be fitted.
During WW2 these were adapted as specialised ground equipment for the Messerschmitt Me 163 Komet rocket-powered fighter aircraft. Early models of this did not have wheels, but took off on a starting dolly, which was jettisoned after take-off. The Scheuch-Schlepper was adaptable to tow the plane on its starting dolly, or with a special lifting device fitted, could act as a recovery vehicle for the Komet after it had landed.