The brakes use a hydraulic dual-circuit brake system with power assistance. The front wheels have disc brakes, that are – except for the 518i – internally ventilated. All models with 2.5L or more displacement have rear disc brakes (non-vented), while the lesser powered models have rear drum brakes. To prevent the wheels from locking, BMW equipped the E28 after 1984 with an anti-lock braking system, although it was an option in some markets.