toyota engineers (including dr kumabe) had visited germany before world war ii and had studied the 16-cylinder auto union racing car (independent suspension) and porsche and volkswagen designs (independent suspension, aerodynamic bodies, backbone chassis, rear-mounted air-cooled engines, economical production cost). many japanese companies had ties with germany during the war years but most partnered with british or american companies after the war and thus used technologies commonly used in britain or america. but toyota did not partner with a foreign company, so it was free to use german designs. many features of the prototype beetle were subsequently put into the sa, although the beetle's rear-mounted air-cooled engine feature was not used. later on, toyota revisited the economic principles exemplified by the beetle when designing the publica and the corolla.