For many years he worked in the American automobile industry and returned to Sweden in 1924.
His experiences in the American automobile industry was probably the main reason why Gustav Larson asked him to join the team of engineers that started the design work for Volvo's first automobile, ÖV 4, in 1924.
A lot of Jan G. Smith's original drawings for the Volvo ÖV4, the gearbox, the main chassis components and technical papers that he had collected in America in the form of a private design book, are saved in the archive of the National Museum of Science and Technology, Stockholm, Sweden.
After the Volvo project he was employed by ASEA in Västerås and later worked for the same company in Stockholm.
Jan G. Smith was awarded a gold medal in 1929 by the Royal Swedish Academy of Engineering Sciences (IVA), together with Gustav Larson, "for their contribution to the national automobile industry in Sweden".