Josef Hausner, an engineer in the PTT automobile department, designed the Alpine Car IIIa in 1952. The company wanted to get away from the previous alpine car with its fabric sliding roof: expensive to maintain, draughty with the roof open and poor heating results in winter. Hausner found the solution in the form of the "glass car". The rear window area and roof edge were kept transparent with smoke-colored Plexiglas for an unobstructed view of the mountains. An air duct ran through the middle of the roof, allowing fresh air to flow into the passenger compartment via dynamic pressure or a blower. From 1953 to 1955, Eggli, Frech-Hoch, Gangloff, Hess, Lauber, Ramseier+Jenzer and Saurer built 41 Alpenwagen IIIa on the Saurer L4C chassis. Individual vehicles remained in service until 1976.