Erwin Komenda, Ferdinand Porsche's first car-body designer, was forced to develop an all-new unitized bodytub structure, since the flat floorpan chassis of the existing VW vehicles was unsuited to smooth movement through water.The initial Schwimmwagen, Type 128 prototype, was based on the full-length Kübelwagen wheelbase of 2.40 m (7 ft 10 in).Pre-production units of the 128, fitted with custom welded bodytubs, demonstrated that this construction was too weak for off-road use.15,584 Type 166 Schwimmwagen were produced from 1941 through 1944; 14,276 at Fallersleben and 1,308 by Porsche; the VW 166 is the most-produced amphibious car in history.As with the Kübelwagen, the Schwimmwagen had rear portal axles, which provided increased ground clearance, while at the same time reducing drive-line torque stresses with their gear reduction at the wheels.