6. GM Futurliner – $4.4 Million
One of the craziest but still roadworthy concept cars was the famous GM Futurliner bus. They unveiled it in 1939 as a part of the Parade of Progress, which was the predecessor to the Motorama traveling show. Amazingly, those Futurliners were custom-made buses that used a regular GM Truck Division drivetrain.
Redesigned for the ’50s, Futurliners gained a recognizable shape. Also, they designed each one of them to show a specific technology or achievement. The interior featured an information desk and could accommodate visitors. GM produced 12 of those vehicles. But only nine of them survived. And one of them sold recently for a staggering $4.4 million.