The Ford Nucleon concept car.
The Ford Nucleon was a scale model concept car developed by Ford Motor Company in 1958 as a design on how a nuclear-powered car might look. The design did not include an internal-combustion engine, rather, the vehicle was to be powered by a small nuclear reactor in the rear of the vehicle, based on the assumption that this would one day be possible by reducing sizes. The car was to use a steam engine powered by uranium fission similar to how nuclear submarines work.
The mock-up of the car can be viewed at the Henry Ford Museum in Dearborn, Michigan.
In Popular Culture 
The Nucleon is the inspiration for the nuclear cars (such as the fictional Chryslus Corvega, which in-game billboards describe as having an "Atomic V8" engine) scattered throughout the landscape of the Fallout series. The games' depiction is more satirical however, showing the safety problems this would likely cause by having the cars explode in a mushroom cloud and release radiation when shot at by players or enemy NPCs.