BMW introduced their Manual 633CSi variant of the E24 6 Series for the 1978 model year. The 633CSi replaced the BMW 630CSi, and was powered by BMW's M30B32 engine. This 3.2L inline six was the only engine used for the 633CSi, but depending on tuning, its power ranged from 174hp to 197hp. European spec versions featured more power than North American variants due to different fuel injection and catalytic converters. These differences were due to US emissions regulations. Initially, power was sent to the rear wheels via a 4 speed manual gearbox, but from the 1981 model year, a 5 speed transmission was used. Production of the Manual-equipped BMW 633CSi lasted until 1984.