This undated photo shows the Gyron, a two-wheeled concept car developed by Ford Motor Company. Initially shown off at 1961's Detroit Motor Show, it had two in-line wheels like a motorcycle, and two side-by-side seats inside the cab. A system of gyroscopes was supposed to keep the vehicle stable, but in practice, it needed outriggers to keep upright on the road. It was never put into production.
Source: https://www.forbes.com/sites/davidewalt/2012/11/14/the-two-wheeled-ford-that-never-was/>