Suspension, steering and brake systems The suspension of passenger cars has a major influence on ride comfort. Small passenger vehicles mostly use leaf springs, supplemented by shock absorbers, large passenger cars with leaf springs, and hybrid suspension devices using air suspension or leaf springs and air elements. The air suspension device has good shock absorption and comfortable ride. In general, a body height adjustment valve is also installed so that the height of the floor can be automatically adjusted with the load change, and the passengers can get on and off the vehicle more conveniently.

The load on the front axle of passenger cars is generally high, and steering devices are equipped with pneumatic or hydraulic power steering devices. The installation of a power steering gear not only makes the steering manoeuvre light, but also reduces the reverse impact. In order to ensure safe driving and reliable braking, passenger cars generally adopt dual-line brake systems, and some also have auxiliary brakes, such as exhaust brakes and electric turbine speed reducers. Since the 1970s, electronically controlled anti-wheel locking devices have begun to be used on passenger cars.

Many countries actively encourage the use of passenger cars instead of cars in order to solve the problem of heavy traffic, serious pollution, and high energy consumption caused by too many cars. For this reason, passenger cars must not only improve performance such as power, safety, and fuel economy (see car use performance), but also must focus on improving ride comfort so that it can meet or exceed the level of a typical car.