automatic transmission

Both the xDrive35i and the xDrive50i use an 8-speed automatic transmission, first introduced in the 5-series Grand Turismo. Brake energy regeneration is also used on both gasoline engines, which uncouples the alternator from the accessory drive system, allowing the battery to only be charged during coasting or braking. This, BMW says, results in up to 2 percent fuel economy boost. The X5 M features a 6-speed automatic as the only transmission option.