Isothermos was founded in 1939 for the production of refrigerators and heaters. After the war their production turned into motorcycles and the company name changed in Iso Automotoveicoli Spa. In 1953 they presented the famous Isetta, the little two-seat car that had a lot of success in Italy and in Europe, where it was manufactured under Iso license by other car industries (such as BMW in Germany).

In the 1960s the firm started producing fast Grand Tourism cars that united the Italian style and manufacturing technics with the high performances guaranteed by the big American V8 engines in one car.

Designed under Giotto Bizzarrini direction, the Rivolta GT IR 300 prototype was introduced in June 1962. With an elegant body designed and constructed by Bertone, this car started being produced in 1963 and was the Grand Tourism car that had the greatest commercial success for the factory.