Wikipedia’s entry for GM Futurliners explains that these wild custom vehicles were designed in the 1940s for General Motors by the legendary Harley Earl:
Originally manufactured for the 1939 New York World’s Fair, the Futurliners were later featured in GM’s Parade of Progress, a promotional caravan travelling a 150-stop route across the United States and Canada. The Futurliners, along with 32 support vehicles, were driven by 50 college graduates, who also staffed the exhibitions along the route.
Typically arranged at each stop around a large tent and an information kiosk, each Futurliner featured a self-contained stage as well as a prominent deployable light tower, and each vehicle featured a particular subject. The mobile exhibition covered such topics as jet engine technology, agriculture, traffic engineering, stereophonic sound, microwave ovens, television and other innovations.
At 33 feet long, 8 feet wide, more than 11 feet tall, and weighing more than 12 tons, each Futurliner featured heavily stylized art deco, streamlined bodywork, deep red side and white roof paint, large articulated chrome side panels, a military-grade 302 cubic inch GMC straight-six gasoline engine and automatic transmission, whitewall tires and a prominent, high-mounted, centrally located driver command position with a panoramic windshield.
There are only nine of these left & the last one to sell sold for a cool $4 million!! Photos & more info at Wikipedia. You may also enjoy the many pics & stories including a restoration project at Futureliner.org.