In the 1950s the lorry and bus model selection diversified heavily and diesel engines became more common pushing aside the self-produced petrol engines. For a short time in late 1940s Hercules diesels were used, but as soon as their production ended, SAT was forced to find new power options. West German Henschels proved sturdy engines, but their power-to-weight ratio was not good, and moreover, the vehicle structures suffered from the heavy engine. Henschel was finally dropped off from the selection because the weakening Finnish mark in relation to German mark made them too expensive.