What is adaptive cruise control?

Published: 13 July 2023

You may have heard terms such as ‘adaptive cruise control’ or ‘active cruise control’ when looking at a car’s list of features but what do they mean, how do these systems work and how do you use them? Our guide explains.

Adaptive cruise control (ACC) is an increasingly popular driving assistance feature that controls a car’s accelerator and brakes to reduce the stress of driving. Unlike traditional cruise control, which maintains a set speed, adaptive cruise control reacts to the traffic ahead, slowing or accelerating accordingly.

Some manufacturers use brand names, such as Active Cruise Control (BMW), Adaptive Cruise Assist (Audi), Distronic (Mercedes-Benz), Dynamic Radar Cruise Control (Lexus), Intelligent Cruise Control (Nissan) and Smart Cruise Control (Hyundai).

The key word is ‘adaptive’. Standard cruise control allows you to select a speed, say 70mph, and your car will maintain that speed until you press the ‘Cancel’ button or the brake pedal. In most cases, it’s also possible to increase or decrease the set speed using buttons on the steering wheel.

ACC goes further by detecting the traffic ahead of you and maintaining a safe distance to the vehicle in front. In most cases, it can either reduce or lengthen the gap to suit the speed you’ve set or the road conditions.

ACC uses radar or laser sensors mounted on the front of the car – usually in the grille or at top of the windscreen – to scan the road ahead for other vehicles. (It’s a bit like Michael Knight’s KITT from the ‘Knight Rider’ TV series in the 1980s, but without the red strobe light!)

These sensors continually work out how far your car is from the vehicle in front and then your car’s computer ‘brain’ works out whether to accelerate or brake to maintain a set distance from it.

To use ACC you simply accelerate to your desired speed and push the ‘Set’ button, or select a speed using the ‘+’ and ‘-’ buttons, allowing the car to accelerate on your behalf. The car will maintain the same speed until the radar or laser ‘locks on’ to a slower car in front, at which point it will follow at a safe distance.

If the vehicle ahead speeds off or exits the road, your car will return to the original speed. On some cars, the adaptive cruise control can be used in slow-moving traffic, automatically accelerating or decelerating to follow the car in front, and even stopping and restarting when required. We’re not saying it makes traffic pleasurable, but it certainly reduces the hassle of braking and accelerating in stop-start traffic.

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An increasing number of cars have adaptive cruise control, either as standard or as an optional extra. Even the Vauxhall Corsa – one of Britain’s most affordable cars – has it on high-spec trim levels when bought new.

The most obvious way to see if your car has adaptive cruise control is to look on the steering wheel (or sometimes on a stalk behind the wheel). Buttons and switches marked ‘Cruise’, ‘Cancel’, ‘Res +’ and ‘Set –’ are tell-tale signs of a cruise control system, along with a digital display on the instrument panel. However, these are used to control standard cruise control systems as well as adaptive setups. Adaptive systems tend to also have a button or switch to control the distance maintained between cars, so that’s the one to look for.

Of all the driver assistance systems, adaptive cruise control is one of the most useful, particularly on a long journey. If nothing else, it gives your right leg a rest, which is normally something only your left leg can enjoy. It’s also more relaxing knowing that you won’t go over the speed limit and that your car will automatically react to changing traffic conditions. Some adaptive cruise systems only work down to a certain speed, but others will keep controlling the car even to a standstill.

It also acts as a safety net of sorts. While you should always pay attention to the road ahead, adaptive cruise control can provide an early warning system if the traffic slows.

While it’s not a disadvantage as such, ACC could be used as an excuse for a driver to pay less attention to the road ahead. Like all driver assistance systems, adaptive cruise control should be used as a driver aid, not as an opportunity to ‘switch off’ behind the wheel. None of the systems are infallible, and are no substitution for paying attention.

And some people simply don’t like the feeling of their car accelerating and braking for them since it might not react exactly as they would. If that’s the case, you can always choose not to switch the system on.

Car manufacturers spend millions of pounds on research and development to ensure that driver assistance systems are safe to use. As such, when used correctly, a car with ACC is arguably safer than one without.

It’s important to always remain in full control of your car. While your right leg might enjoy some downtime, your eyes and ears shouldn’t. Unless your car has lane-keeping assist, you’re still required to steer it! Even if it does have that system, your hands will need to be on the wheel.

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