Cugnot was one of the first to employ successfully a device for converting the reciprocating motion of a steam piston into rotary motion by means of a ratchet arrangement. A small version of his three-wheeled fardier à vapeur ran in 1769. (A fardier was a massively built two-wheeled horse-drawn cart for transporting very heavy equipment such as cannon barrels).
The following year, a full-size version of the fardier à vapeur was built, specified to be able to carry 4 tons and cover 2 lieues (7.8 km or 4.8 miles) in one hour, a performance it never achieved in practice.
The vehicle was reported to have been very unstable due to poor weight distribution which would have been a serious disadvantage seeing that it was intended that the fardier should be able to traverse rough terrain and climb steep hills. In 1771, the second vehicle is said to have gone out of control and knocked down part of the Arsenal wall, (the first known automobile accident. (source: wikipedia.org)