Pierre Dreyfus defined the brief for the new Renault R4 to replace the rear-engined 4CV in 1956; He considered the air-cooled cars from Citroen and VW and chose to go with the existing Ventoux engine from the 4CV but adapt it to front wheel drive. In 1961 the new Renault was launched with a 603cc unit as the Renault 3, and with the existing 747cc unit from the 4CV as the Renault 4. On both the lower-priced cars a window in the c-pillar was an optional extra. From 1963 the 845cc engine based on the Dauphine unit was offered and soon became the default engine when the Renault 3 and the basic Renault 4 were dropped. Renault developed a new gearbox for the car, with a dashboard-mounted gearlever extending forward to the gearbox at the front of the engine, but it only had 3 speeds until 1968. Torsion bar suspension gave each wheel independent springing and intriguingly gave a slightly different wheelbase on each side of the car due to the positioning of the bars behind each other underneath. From 1978 Renault 4 GTLs were given an 1108cc Sierra engine from the Renault R8, and a 956cc version of this unit replaced the 845cc Ventoux unit from 1986. The Renault 4 was supposedly replaced by the Renault 5 in 1972, but was kept in production in different locations until 1992 when 8 million had been sold