The car's safety systems

Modern cars have a range of active and passive safety systems that assist the driver and protect occupants. The theory test tests whether you understand what they do and what limitations they have.

Active and passive systems

ABS (Anti-lock Brakes)

ABS prevents the wheels from locking during hard braking. The benefits are:

• You keep steering during braking
• Braking distances can be shorter on dry and wet roads
• On loose snow and gravel, the braking distance can be longer than without ABS

ABS is activated automatically and feels like a pulsation in the brake pedal. Hold the pedal and do not let go.

ESC (Electronic Stability Control)

ESC prevents skidding by braking individual wheels and reducing engine power. The system is mandatory in all new cars in the EU.

ACC (Adaptive Cruise Control)

The ACC maintains a set speed and automatically adjusts the distance to the car in front:

• Slows down when the vehicle in front brakes
• Accelerates when the road ahead is clear
• Some systems can handle congestion
• ACC doesn’t replace the driver’s attention

LKA (File Assistant)

LKA warns if the car is about to leave the lane without the turn signals activated. Some systems gently steer the car back. The system works best on roads with clear markings.

AEB (Automatic Emergency Braking)

AEB detects obstacles in front of the vehicle and brakes automatically if the driver does not react. The system can:

• Significantly reduce the collision speed
• In some cases, avoid the collision altogether
• Works best at low and moderate speeds

Limitations You Must Know

All assistance systems have limitations:

• They perform less well in poor visibility, snow or rain
• Sensors can be blocked by dirt and ice
• The systems are aids and do not relieve the driver of responsibility
• Daily Check includes checking that the warning lights for these systems are not lit

Keep the sensors clean and read the instrument panel regularly.

Further reading

• Electronic Stability Control for details of ESC/ESP
• Brakes and braking system about ABS and braking power
• Seat belt and airbag on passive safety systems
• Electric cars and hybrid cars in traffic on regenerative braking and AVAS
• Engine brake and brake conditions on the interaction between brake and electronics