The Citroën Traction Avant was the world’s first unibody front-wheel-drive car. They were made 1934 to 1957. Approximately 760,000 units were produced. Traction Avant, which translates as "front wheel drive", is not the official name. The car was named according to the French fiscal horsepower rating, or CV, used to determine annual car tax levels. However, manufacturers did not change the model name every time a change of engine size caused a change in fiscal horsepower. In 1934, Citroën introduced the type 7, unofficially the 7A. They continued calling the car 7 when the 7B model's larger engine pushed it into the 9 CV tax band.