What You Need to Know About Adaptive Cruise Control

Last Updated: Oct 6, 2010

What is adaptive cruise control?
Adaptive cruise control works much like normal cruise control; it keeps your car at a set speed without having to use the accelerator. But adaptive cruise control takes it a step further by using radar or a laser to keep a preset distance between you and the car in front, in addition to maintaining a set speed.

The forward-looking radar or laser unit is usually mounted just behind the grille at the front of the vehicle or inside the car between the rear view mirror and windshield. On the open highway with no traffic ahead, adaptive cruise control works no differently than the cruise-control systems automobiles have had for decades. However, once another car is in front of your car, the adaptive system’s radar “sees” the car ahead and matches its speed if it’s lower than your car’s set speed. For example, if you have your car’s cruise set to 80 mph and the car ahead is going 70, the adaptive system will slow your car to 70, while maintaining a distance of a few car lengths to several car lengths, depending on how you’ve set the controls. If the car ahead speeds up to 76 mph, your car will accelerate to 76 mph, again maintaining the interval you’ve dialed in.

Once the car ahead moves out of your lane or accelerates beyond your car’s set speed, the adaptive cruise control system allows your car to return to its set speed – in this case 80 mph. None of this requires any action from you other than to turn on the system and dial in your desired interval, which can be adjusted as you drive to suit conditions. An activated adaptive cruise-control system is typically represented in your instrument cluster by a depiction of your car and a graph showing the interval options available. Like a conventional cruise-control system, the adaptive system disengages as soon as you press the brake pedal or manually cancel your set speed.

How does adaptive cruise control help me and my passengers?
The benefit of adaptive cruise control is most obvious on a highway with light to moderate traffic. Because the adaptive system automatically slows your car when traffic slows, it means you can more easily maintain a safe distance between you and the car ahead. Most adaptive systems allow you to set how large that gap is by using a steering-wheel-mounted button.  

Both driver and passenger can benefit from adaptive cruise control if it reduces well-meaning declarations of “you’re following too close.” And on long trips, using adaptive cruise control will likely reduce driver fatigue. That’s because all the slight adjustments in speed to accommodate other traffic are done automatically. With a manual cruise control system, you have to constantly fiddle with a button, steering-column stalk, or the brake pedal to cancel or disengage the system or to slow down then speed up. With an adaptive system those little changes in speed are done automatically.

Is adaptive cruise control a must-have on my car?
If you’re a driver who never wants to feel excluded from the minute-to-minute decisions that driving requires, you may not like adaptive cruise control. If you rarely hit the highway or drive primarily in urban or suburban settings, adaptive cruise control probably isn’t for you. But if you take frequent road trips or travel long distances by car as part of your job, then yes, adaptive cruise control is a must-have feature. It probably will become something you cannot live without.

Although adaptive cruise control is a great piece of technology, it isn’t perfect. Because it is radar- or laser-based, it can only “see” in a straight line. Occasionally, this limitation means the vehicle will slow unnecessarily. For example, if you’re driving in a straight line and the highway ahead curves to the left, cars making that natural bend in the road will trigger the system to slow your car because other cars appear to be directly in front of you. The adaptive cruise system doesn’t know the road ahead bends and cannot see that the car ahead is in a different lane. Also, the radar based cruise system may not work well in heavy rain or snow.

Adaptive cruise control used to be available only on cars from high-end brands like Jaguar and Mercedes Benz. Today, the feature is standard on some expensive models but increasingly common on more mainstream cars. It isn’t cheap, though, typically running more than $1,000 as a stand-alone option or even more when bundled in a package with other extra-cost features.

The 2011 Ford Taurus Limited offers adaptive cruise control as a stand-alone option at $1,195. And while the 2011 Toyota Sienna minivan has a base price of under $25,000, you have to move up to the $39,500 Sienna Limited model to add adaptive cruise control. Even then it’s part of a $1,800 technology package. The top trim level of the Acura RL premium sedan with the Technology Package and collision avoidance system is one of the least expensive cars to offer adaptive cruise control as a standard feature. That RL may be a bargain in the world of luxury sedans, but it still costs $54,000.

As in the Acura RL, adaptive cruise control is often combined with a collision avoidance system that automatically applies the brakes if the car’s computer calculates that an accident is about to happen. Even though they may be grouped, adaptive cruise control isn’t the same thing as collision avoidance. Many adaptive cruise control systems will slow your car to 30 mph or so, but the system can disengage if traffic slows below that. In other words, adaptive cruise control isn’t an auto-drive feature for stop-and-go driving; it’s mainly for highway travel.

Automatic vehicle systems like adaptive cruise control are supposed to make driving safer. While many drivers are starting to resist too much technology inside their cars, adaptive cruise control is a system that really works because it adds a layer of safety to what’s typically been a luxury or convenience feature. Adaptive cruise control is safer because a radar and computer system never gets distracted, never follows too close and keeps the same distance between your car and the car ahead every time. Still, there’s no substitute for a human driver; the radar system’s lack of ability to see the whole picture and around corners is the perfect example. The truth is adaptive cruise control works best for drivers who see it not as a way to be removed from the process of driving but for those who remain focused on the road but want an extra margin of safety.