One of the craziest but still roadworthy concept cars was the famous GM’s Futurliner bus. GM designed it in 1939 as a part of the Parade of Progress, the predecessor to the Motorama traveling show. Futurliners were custom-made buses that used a regular GM Truck Division drivetrain.
With a redesign for the ’50s, Futurliners gained a recognizable shape. GM designed each one of them to show specific a technology or achievement. The interior featured an information desk and could accommodate visitors. GM produced 12 of those vehicles and nine of them survived.