It had a 4-cylinder engine, 4-wheel independent suspension and a smaller, aerodynamic body. The project was driven by Kiichiro Toyoda, but most of the design work was done by Kazuo Kumabe. The two-door body was aerodynamic in a style similar to the Volkswagen Beetle. The doors were hinged at the rear (often called suicide doors). The front window was a single pane of flat glass with a single wiper mounted above the driver. Only right hand drive was offered. Toyota engineers (including Dr Kumabe) had visited Germany before World War II and had studied 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 unlike other Japanese car firms Toyota did not partner with Western companies after the war, 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 1950s successors to the SA and the later Publica and Corolla. In the post war austerity of the late 1940s, when most of the Japanese population could not afford a car, but could afford a motorcycle, the Japanese codified a legal standard for extremely economical small cars, known as the keicar. The aim was to promote the growth of the car industry, as well as to offer an alternative delivery method to small business and shop owners. Originally limited to a mere 150 cc (100 cc for two-strokes) in 1949, dimensions and engine size limitations were gradually increased (in 1950, 1951, and 1955) to tempt more manufacturers to produce kei cars. It wasn't until the 1955 change to 360 cc as the upper limit for two-strokes as well as four-strokes that the class really began taking off, with cars from Suzuki Suzulight (front-wheel drive based on the German Lloyd with a DKW type engine) and then Subaru 360, finally able to fill people's need for basic transportation without being too severely compromised. Early generation keicars on the market were mostly rear-engined, rear drive RR layout cars. From the end of the 1960s Keicars switched to front-engined, front-wheel-drive FF layout. This market has thrived ever since, with the cars increasing in size and engine capacity, including sports cars such as