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 Car alpin with its fabric sliding roof: expensive to maintain, drafts 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 mountain world. An air duct ran through the middle of the roof, allowing fresh air to flow into the passenger compartment via dynamic pressure or a fan. Eggli, Frech-Hoch, Gangloff, Hess, Lauber, Ramseier+Jenzer and Saurer built 41 Alpenwagen IIIa on the Saurer L4C chassis between 1953 and 1995. Individual vehicles remained in service until 1976.