The AC Petite was a three-wheeled microcar with a rear-mounted 350 cc Villiers single cylinder, two stroke engine. The cars had a single bench seat seating two adults and was said to be capable of 60 mpg-imp (4.7 L/100 km; 50 mpg-US) to 70 mpg-imp (4.0 L/100 km; 58 mpg-US) and 40 mph (64 km/h).

There were two versions of the car. Between 1953 and 1955 the car was fitted with a Villiers 27B engine and two different sizes of wheel, the rears were 18 inches (460 mm) spoked wheels whilst the front was only 8 inches (200 mm). In 1955 a Mark II version was launched, this had minor changes to the exterior trim, a slightly more powerful Villiers 28B engine and 12 inches (300 mm) wheels both front and rear.