Who built the first self-propelled vehicle (steam automobile) in 1769?

Nicolas-Joseph Cugnot built the first working full-size self-propelled mechanical land vehicle, a steam automobile, in 1769.

Cugnot was a French military engineer who designed his three-wheeled “fardier à vapeur,” or steam dray, to haul heavy artillery for the French Army. A small working version was built and used in 1769. A larger full-size vehicle followed in 1770 and was intended to carry several tons of equipment.

The vehicle placed its steam boiler and engine over the single front wheel, with two supporting wheels behind it. A ratchet mechanism converted the piston's back-and-forth motion into rotation. It was slow, unstable, and had to stop frequently to rebuild steam pressure, so it never became a practical military transport.

Cugnot’s achievement is sometimes qualified because Ferdinand Verbiest may have designed an earlier small steam-powered model in the 17th century. That device was not a full-size vehicle capable of carrying a driver or useful cargo. James Watt improved steam engines, while George Stephenson and Richard Trevithick came later in railway and steam-vehicle development.