• AEB systems will slow and apply brakes to a vehicle if a driver gets too close to minimize the effect of a collision.
• FCW systems will warn the driver they are getting too close to a vehicle too quickly but will not slow or stop the vehicle.

Some systems go one step further than adaptive cruise control (ACC) and will slow the vehicle if there is a hazard in front of it, even when the cruise control is off. The more advanced of these systems will not only communicate with the engine to slow the vehicle when there is a hazard in front of the vehicle, but will also apply the brakes to prevent or minimize the effects of a collision (if the driver does not respond to a system warning). These systems are referred to as automatic emergency braking, or AEB.

Because of the level of integration that is necessary, ACC and AEB are best installed as an original equipment manufacturer (OEM) option. Aftermarket installation is possible but can be difficult.

Collision warning systems (CWS) use radar, sonar, infrared, video, or laser technology to warn the driver when the vehicle is getting “too close” to another vehicle or an object but do not slow or stop the vehicle. It is important to know which system is installed in the vehicle. AEB will slow or stop the vehicle, while CWS will only warn the driver that they are getting too close to a vehicle.

These warning systems also require mounting of hardware (the sending unit, the processor, and the display), electrical connections, and calibration on installation. Most vehicle OEMs are now offering these systems as an option. This is preferred to aftermarket installation, for integration reasons, but may not be preferred for cost reasons (aftermarket installation may be cheaper is some cases). These units are mostly self-contained, and do not require anything from the vehicle except electrical power.