That same year, on 26 December, his father died, and Kässbohrer took control of the business together with his brother, Karl, who was studying for an engineering qualification at the time.
In 1928 Kässbohrer purchased an Ulm coach building firm called Neuner & Thieme which had run into difficulties.
At this time monocoque bodied cars, inspired by the pre-war Opel Olympia, were beginning to appear, and applying equivalent structural approach to motor coaches was a logical extension of this development in the auto industry.
Just two years later, at the 1953 Frankfurt Motor Show, Setra presented Europe’s first articulated bus, with space, it was claimed, for 170 passengers.
A feature of the Setra buses that was unusual at that time was their rear-mounted engines, which made it possible to incorporate relatively low floors and doors along most of the length of the passenger cabin.