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What Is Cruise Control?

Posted by Auto.com Staff | Jan 3, 2019

Cruise control is the capability of setting a vehicles speed and allowing it to continue maintaining that speed indefinitely. The mechanics behind cruise control systems have evolved over the years, but all are based on that core function. Driving with the cruise control can reduce driver fatigue when traveling longer distances.

The idea of maintaining engine speed is not new, with the concept dating back to early steam engines in the 1700s. But getting a steam-power generator to hold a steady output under varying load is quite a different task than controlling the speed of a moving vehicle. Early cruise control systems often relied on an actuator (frequently vacuum controlled) to adjust throttle based on various sensor inputs. Over the years, technology has improved to the point where a car’s Engine Control Unit can now hold a its speed at a set rate as designated by the driver.

These systems are designed with a series of safety concerns in mind, which is why all cruise control configurations are required to disengage when the driver presses the brakes. This automatic deactivate feature is also applied to the clutch in some manual-transmission vehicles. But if you have ever had to travel long distances on an open highway, cruise control can make the drive less stressful. The controls are typically located on or near the steering wheel, and modern cruise control setups let the driver accelerate or decelerate with a push of a button, rather than having to tap the brakes and reset their desired speed manually with the gas pedal.

Some modern iterations, referred to as adaptive cruise control, now use radar or lidar to allow the car to slow down or speed up to match the speed of the car in front of them. First introduced by Mercedes-Benz back in 1999, adaptive cruise control is distinguished from other similar systems by its use of both throttle position and the brakes to control speed. The features can vary between manufacturers, with some systems working all the way to a complete stop, where others only work down to a set mph speed. Increasingly, automakers are pairing these adaptive cruise control systems with other driving safety features, such as forward collision warning or pedestrian warning alerts.

If shopping for a car, you’ll want to make sure and ask just what features come standard, and what kind of cruise control setup is available on the car you are looking at.