Adaptive Cruise Control: How It Works and Why You Need It

The Next Best Thing to Autopilot For Cars

adaptive cruise control maintains distance
Adaptive cruise controls systems allow vehicles to automatically maintain an appropriate following distance. Michael H / Stone / Getty

Adaptive cruise control, also called autonomous cruise control and radar cruise control, is the next evolution in automated speed management in your car. These systems are capable of automatically adjusting the speed of a vehicle to match the speed of the car or truck in front of it. If the lead vehicle slows down, adaptive cruise control can automatically match it. When traffic picks back up, these automatic systems are also capable of acceleration.

How Does Adaptive Cruise Control Work?

Cruise control is a relatively simple system that allows a driver to adjust the position of the throttle without using the gas pedal. It has been around for a very long time, and it often helps improve fuel economy at highway speeds. However, drivers who use cruise control have to remain constantly vigilant against the actions of other drivers. Most cruise control systems will shut off if the driver taps the brakes, but they aren’t capable of making automatic adjustments to the speed of a vehicle.

Adaptive cruise control is similar in design to more traditional systems, but there are a few additional components in play. Instead of relying on driver input, adaptive cruise control systems make use of laser or radar sensors. These sensors are capable of detecting the presence and speed of other vehicles, and that information is used to maintain a safe following distance. If adaptive cruise control detects an obstruction in the roadway, or the lead vehicle slows down, the system is capable of cutting the throttle, downshifting, and even activating the brakes.

What Vehicles Come with Adaptive Cruise Control?

The first vehicle with adaptive cruise control shipped in 1995, but the technology is still in its infancy. About a dozen automakers offer some type of adaptive cruise control, and most of the holdouts at least have something on the drawing board. However, the availability of fully adaptive cruise control is even more limited.

BMW was one of the first automakers to offer fully adaptive cruise control, which is capable of bringing a vehicle to a complete stop. This option has been available on 7 series, 5 series, and 6 series BMWs since 2007. Mercedes, Volkswagen, GM, and a handful of others have also rolled out their own fully adaptive cruise control systems.

In most cases, the adaptive cruise control option is limited to only a few models in each OEM lineup. A classic example is GM, which initially limited the option to its upmarket Cadillac badge. Then starting with the 2014 model year, a fully adaptive system was also available for the Chevy Impala.

How Do I Use Adaptive Cruise Control?

If you’ve used regular cruise control, then you should have a pretty good idea of how to use adaptive cruise control. In fact, some vehicles provide you with the option to operate in a standard cruise control mode. The specific controls will vary depending on your particular vehicle, but you will usually have to start by setting a cruising speed. In some cases, you will then have to specifically turn on the adaptive system.

Since adaptive cruise control uses radar or laser sensors to monitor the speed and position of the vehicle in front of yours, you are free to focus on maintaining your lane position and checking for other hazards. It’s still necessary to remain vigilant, but a functional adaptive cruise control system does take some of the pressure off.

If your vehicle is equipped with a partially adaptive cruise control system, you’ll have to keep an eye out for traffic jams and other hazards. These systems usually shut down after your vehicle slows down to a certain speed, so they aren’t capable of bringing you to a complete stop. Fully adaptive systems, like those found in late model BMWs, are capable of functioning in stop and go traffic.

Does Adaptive Cruise Control Really Make You Safer?

Adaptive cruise control can help reduce the likelihood and severity of rear-end collisions, but these systems are still relatively limited. Distracted drivers are likely to fail to manually adjust their cruise control settings in time to avoid collisions, so adaptive cruise control can be a huge benefit in those situations.

However, adaptive cruise control can actually cause a reduction in safety if the driver isn’t aware of the limitations of the system. According to a study performed by AAA, an alarming number of drivers are unaware that their partially adaptive cruise control systems are incapable of completely stopping their vehicles. Other drivers are unaware that adaptive cruise control doesn’t work properly on winding roads because it can pick up vehicles in other lanes. If you’re fully aware of all those limitations, then adaptive cruise control will make you safer.

What Types of Adaptive Cruise Control Are Available?

Adaptive and autonomous cruise control systems can be broken down into laser- and radar-based systems, and they can also be differentiated based on the amount of input required from the driver.

Laser-based autonomous cruise control systems use a front-mounted laser to track the position and speed of other vehicles. Due to the limitations of using a laser, these systems often have trouble detecting vehicles are are dirty or otherwise non-reflective, and bad weather can also adversely affect the ability of a laser-based system to track other vehicles.

Radar-based systems are sometimes called radar cruise control, and they use one or more radar sensors instead of a laser. These typically work in a wider range of weather conditions and are typically capable of tracking other vehicles regardless of reflectivity.

Some adaptive cruise control systems are also integrated with precrash technologies, like adaptive braking, and other ADAS like lane departure warning systems.

What Happens When Adaptive Cruise Control Fails?

A potential failure is the main reason that you need to remain vigilant. If your system fails while it’s in use, you will have to manually adjust your speed. The vehicle will still be safe to drive, but you won’t be able to rely on the adaptive system to automatically maintain your following distance.

It’s also vital to understand that some systems can fail even if they appear to be working fine. If your adaptive cruise control uses a laser sensor, then you need to be aware of the fact that it may fail to properly track other vehicles in adverse weather. Laser sensors can also fail to track vehicles if they’re especially dirty or use non-reflective paint. Radar-based adaptive cruise control is typically capable of tracking vehicles regardless of paint or weather conditions, but none of these systems are infallible.

Where is Adaptive Cruise Control Going in the Future?

Today, adaptive cruise control systems are capable of functioning without any outside input. They simply use a sensor to detect the position and speed of other vehicles and make the necessary adjustments.

In the future, we may see cooperative adaptive cruise control systems that utilize information from other vehicles and transmit information to other vehicles. An implementation of this type of system would involve one vehicle transmitting speed data to the vehicle behind it, which would in turn transmit speed data to the vehicle behind it, and so on.

The benefit of this kind of advanced adaptive cruise control is that it would not rely on external measurements and sensors that can fail in some situations like current systems. However, the implementation of this type of system would require a tremendous amount of cooperation between automakers and lawmakers and wouldn't work without an across the board adoption of the technology.