The SA was Toyota's first new passenger car design (as opposed to updating the AA) after World War II. It was the first in a family of vehicles before the introduction of the Crown. A series of light trucks also shared the chassis and major components of these passenger cars.

All of these vehicles were sold under the Toyopet name.

=SA= The SA was Toyota's first true post war design. It differed from all previous Toyota cars by having a 4 cylinder engine (previously a 6 cylinder was used), 4 wheel independent suspension (previously using rigid axles with leaf springs) and a smaller, aerodynamic body. The project was driven by Kiichiro Toyoda under the wisdom of his father's (Sakichi Toyoda) words, "Stay ahead of the times" "Toyota: Fifty Years in Motion", Eiji Toyoda, Tokyo: Kodansha International, 1987, ISBN 0-87011-823-4, p119 but most of the design work was done by Dr Kazuo Kumabe. "Fifty Years of Toyota Concept Cars", in "the wheel extended", vol 17, no.3, 1987, Toyota Motor Corporation, ISSN 0049-755X

The body was aerodynamic in a style similar to the Volkswagen Beetle. Only a two door sedan was made, making it unsuitable for the taxi market. The doors were arranged to open rearwards (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 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) "Autos Made in Japan", Jan P. Norbye, Gerlingen: Bleicher Verlag, 1991, ISBN 3-88350-161-1 . 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.