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Adaptive cruise control – what is it and how does it work?

More and more cars come with adaptive cruise control as standard or as an option. What does it do and is it for you?

More and more cars now come with adaptive cruise control as standard or as an option. But what does it do and is it for you?

Traditional cruise control allows you to set your car to drive at a speed you choose (usually above 30mph) which it will then maintain, including up and down hills, while you take your foot off the accelerator. It can be paused and resumed by the driver, and touching the brake pedal will also de-activate it. You still need to keep your hands on the wheel.

First seen in the 1990s, adaptive cruise control (ACC) works on the same principle, but your car watches the road ahead and can reduce and then regain your set speed on its own. It’s the first of four official classes of autonomous driving, or types of self-driving vehicle.

Once the system is switched on (usually available from about 20mph), you set your desired speed then choose the gap you want to leave to the car in front. This is usually done via controls on the steering wheel or a stalk on the steering column. If you want to pause the ACC you press the brake pedal or button.

Adaptive cruise control buttons
Adaptive cruise control buttons on the steering wheel of a Mazda

If you catch up to a car ahead of you, or if another vehicle cuts in front of you, ACC intervenes to automatically slow the car down. When a safe distance opens ahead, or when you pull out to a clear lane, it will bring the car back up to the chosen speed. If very sudden braking happens in front of you, most systems will apply the brakes more severely, or disengage and you must complete braking. You can temporarily override your chosen speed, say for overtaking, by accelerating.

Radar/camera-based ACC systems are the dominant technology, although laser (which builds a 3D picture of the world around the car) will feature on future self-driving cars. Radar can scan the road for objects up to 200 metres ahead and the sensors can be hidden behind the lower part of the front bumper or behind the badge. It can be combined with one or two cameras which use software to analyse the distance ahead and are mounted in the windscreen behind the rear-view mirror.

Pros:

If you often use motorways, then both types of cruise control can make driving easier and help you stick to the speed limit, but ACC is better suited to the heavier traffic of the UK.

It comes into its own paired with automatic transmission because many ACC systems (sometimes called Stop and Go) allow the car to come to a complete halt and after a few seconds move off when there is a clear space. ACC is often allied to Autonomous Emergency Braking, which will stop the car at city speeds.

Cons:

Adaptive Cruise Control is not for everyone. It can take some getting used to the sensation, and to learn how to use the controls. ACC has its limits. Radar cruise control can’t always recognise the shape of the vehicle in front, and can be affected by heavy rain, snow and fog and sharp bends. However, in those situations it’s safer not to use any kind of cruise control at all.

Both cameras and radar sensors (some radars are heated) need to be kept clean to work properly. If any cruise control system malfunctions while driving, it should disengage and you should see your dealer as soon as possible.

Adaptive cruise control radar unit
Adaptive cruise control radar unit on the front of a Volkswagen Golf

How do I get adaptive cruise control?

Carmakers give adaptive cruise control different names. It can also be called active cruise control, intelligent cruise control or distance control. Mercedes-Benz calls it Distronic.

If you’re buying new, regular cruise control is a common standard fit from the supermini class (eg – Ford Fiesta) upwards, but ACC can be found on the options list. Moving up in size, ACC is standard fit on some medium-sized family cars such as the Honda Civic, Volkswagen Golf, Mazda 3, Toyota Corolla and Renault Captur.

Some prestige car makers – such as Land Rover and BMW – prefer to provide cruise control as standard but give buyers a choice on ACC as a factory-fit option. Then it can often be allied with other technologies such as camera software which reads traffic signs and road markings so will keep the car from drifting out of its lane – usually called Lane Keeping Assist – and it can also combine with the navigation system and front and rear cameras to slow the car down for junctions and curves.

Adaptive cruise control can’t be fitted as an accessory. If you’re buying a used car, ACC becomes harder to find unless the first owner specified it as an option when new. However, you can go as far back as a 2012 Volkswagen Golf Mk 7 and find radar ACC on most models, as Volkswagen was then alone in fitting it to that class of car as standard.

To sum up, adaptive cruise control can make long journeys easier, but you need to be prepared to do some homework to get the best out of it. It’s not an invite for a snooze: at any kind of speed, you still need to keep alert, steer and be ready to brake.

Russell Hayes
Russell Hayeshttps://amzn.to/3dga7y8
Russell Hayes’ early career was 14 years of motoring journalism in print, television and online. He worked for What Car? and Complete Car magazines, the BBC's original Top Gear programme and Channel 4's Driven. Since 2007 he has written motoring history books on subjects including Lotus, TVR, the Earls Court Motor Show, the Volkswagen Golf, Volkswagen Beetle and Bus and the original Aston Martin V8. Now a full-time author, two more books are in the pipeline for 2021 and 2022.

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