Can Adaptive Cruise Control Stop Your Car?

Adaptive cruise control (ACC) might sound like just another car safety feature. But this driver aid is actually the first step in autonomous driving. Here’s how adaptive cruise control can improve your commute and might be worth the upgrade.

What is adaptive cruise control?

A car with adaptive cruise control features some type of sensors: radar, lasers, or even cameras. When you switch on cruise control, the vehicle uses these sensors to monitor surrounding traffic and signage, then adapts accordingly.

Timelapse photo of headlights and brakelights blurring down a divided highway.
Lights on the highway | Joey Kyber via Unsplash

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Depending on the car brand you’re shopping for, you may see adaptive cruise control labeled with one of several names. Brand names for adaptive cruise control include dynamic cruise control, radar cruise control, automatic cruise control, intelligent cruise control–according to Car and Driver.

What does adaptive cruise control do?

Early adaptive cruise control (ACC) systems decelerated and downshifted for you when they detected an impending collision. But you had to apply the brakes. Later ACC systems can apply your brakes for you. After the risk of collision has passed, ACC accelerates back up to your set cruising speed.

A crowded rush hour highway filled with commuters at sunset.
Cars on the highway | Alexander Popov via Unsplash

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Adaptive cruise control was once a rare luxury feature. Now you can order ACC on the Mazda 3 and Honda Accord. As this driver aid system becomes more common, several car brands are adding extra features to stand out.

For example, Ford’s BlueCruise offers “Speed Sign Recognition.” This system can actually read upcoming speed limits signs, then adjust your speed accordingly.

Another example, General Motors’ Super Cruise system taps into GPS data on pre-mapped roads. This data enables Super Cruise to prepare for tight corners or upcoming speed limit changes by slowing down for you.

Can adaptive cruise control stop your car?

Not every version of adaptive cruise control (ACC) can fully stop your car. The driver aids capable of stopping your car are often labeled “stop-and-go ACC.”

Cars parked bumper-to-bumper in stop and go traffic between city buildings.
Cars in stop-and-go traffic | Nabeel Syed via Unsplash

The most common adaptive cruise control systems can gently slow your car when you are either approaching another car or a car in front of you slows down. If the car in front of you is driving near your set cruising speed, any ACC should be able to fall in behind them and match their speed. If this car speeds up or gets off the road, ACC will then accelerate back up to your set cruising speed.

When an ACC system without “stop-and-go” encounters a very slow car, or even a parked car, it will slow your car as much as it can. It will also warn you of the impending collision using forward collision warning (FCW) alerts. But it is your job to stop the vehicle. ACC will then shut off and let you take control.

If your ACC system has “stop-and-go” it can stop your car completely. This system is capable of navigating “stop-go” traffic without hitting another car. After stopping fully, your vehicle will then accelerate again, towards your set cruising speed, as fast as traffic will allow.

What is the difference between cruise control and adaptive cruise control?

When you set your cruise control, you choose a cruising speed and your car takes care of acceleration. When you set adaptive cruise control you choose a preferred cruising speed and following distance (often short, medium, or long). Your vehicle cruises at your preferred speed when possible, but prioritizes your set following distance when necessary.

Just like cruise control, adaptive cruise control does not steer for you. So while your car takes care of accelerating, you have to keep your hands on the wheel.

If you don’t have ACC with stop-and-go, you’ll also need to stay vigilant for any pileups or stopped traffic. Just like with regular cruise control, you’ll have to stop your car to avoid any potential collisions.

Learn about how widespread ACC might someday prevent traffic jams in the video below:

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