A steam car is a car (automobile) propelled by a steam engine. A steam engine is an external combustion engine (ECE), whereas the gasoline and diesel engines that eventually became standard are internal combustion engines (ICE). ECEs have a lower thermal efficiency, but carbon monoxide production is more readily regulated.

Ransom Eli Olds was a pioneer of the American automotive industry, after whom the Oldsmobile and REO brands were named. He claimed to have built his first steam car as early as 1887 and his first gasoline-powered car in 1896. The modern assembly line and its basic concept is credited to Olds, who used it to build the first mass-produced automobile, the Oldsmobile Curved Dash, beginning in 1901.