The fourth design took that Sakuyama chassis and engine and replaced the steam system in late 1923 with Charles A. French's patent design. The French-Coats was technically the most superior, probably the most likely to have been functional, and the car used in photographs.
The fourth model built upon the Sakuyama chassis and engine, and in 1923, it integrated Charles A. French's design for a more efficient steam system, which may have been the most sophisticated of its era.