It was a larger-displacement variant of the S360 roadster which, though developed for sale in 1962, was never produced.

[3] It was a dual overhead cam straight-4 with four Keihin carburetors and a 9500 rpm redline.

[2] At the time of its introduction, its dimensions and engine displacement were larger than established kei car regulations.

A four-wheel independent suspension was also novel, with torsion bars at the front and chain-driven, coilover-sprung[2] trailing arms at the rear.

The S500 saw competitors during its introduction, such as the Datsun Fairlady, the Toyota Sports 800, and the Daihatsu Compagno.