What Is Cruise Control In a Car?

As anyone that has ever gone on a long road trip — or even someone that has a long commute to school or work every day — can tell you, driving can be exhausting. Sitting in the driver’s seat behind the wheel for hours on end is enough to tire anybody out physically and mentally. This is especially true if you’re constantly adjusting the force of your foot on the gas pedal manually to account for changes in the speed limit, encountering road hazards, and more. Not only do you have to adjust your speed for various reasons continually, but you may also find yourself mindlessly changing speed without even noticing. 

Have you ever been on a road trip and looked down and saw yourself going 10, maybe 15 miles per hour over the speed limit? Or perhaps you’ve seen the opposite and looked down to see that you were going much slower than you should be. This happens to everyone throughout a road trip as your leg, mind, or both start to tire. Thankfully, cars these days typically come with cruise control to help mitigate these issues.

So what is cruise control?

The easiest way to understand what cruise control is to imagine that enabling it will keep your car at whatever speed it’s moving at when you turn on cruise control. And that’s precisely what it is doing. Cruise control is designed to maintain a consistent speed without requiring you to hit either the gas pedal or the brake pedal unless you need to start slowing down or coming to a stop. 

The concept of cruise control is not a new one by any means, as early forms of the idea were used hundreds of years ago on steam engines to help maintain a steady speed as they traversed up and down inclines. Of course, adding it to cars happened much later, but the majority of vehicles seen on the road today — especially in America — will come factory-equipped with cruise control. 

The ability to cause an automobile to maintain a constant speed may seem like magic or witchcraft, so let’s take a look at how cruise control works.

How does it work?

To understand how cruise control works, it’s essential first to know how a vehicle’s speed is adjusted or maintained regularly. Without cruise control, this is, of course, controlled by the driver of the car by pressing or depressing the accelerator (gas) pedal. When the pedal is depressed, the vehicle’s throttle opens further and allows for more air into the engine, making its speed increase.

With that in mind, cruise control works mainly in the same way. The cruise control system, once enabled, will adjust the throttle position to maintain the speed. Now since the cruise control is an electronically controlled feature, it uses an actuator to automatically adjust the throttle position rather than the pedal that you would use. 

If the car is moving too slowly compared to the speed that it’s set at (like when going up a hill), the actuator will make the throttle open up and allow more air into the engine, causing it to go faster. Conversely, suppose the vehicle is moving too quickly compared to the set speed (like when coming back down that hill). In that case, the actuator will adjust the throttle position to allow less airflow to the entire engine, which will slow the vehicle down.

In most cases, cruise control is engaged and then controlled by pressing a sequence of buttons somewhere on or near the steering wheel that the driver can easily access while driving. You must press the button to engage the system, followed by the SET button, which will set the cruising speed at whatever vehicle’s current speed. The SET button is often right next to the ACCEL or ‘+’ button, which will increase the car’s cruise speed by one mph when pressed. Pressing the ‘-’ button will slow the vehicle down by one mph. 

While that may seem like a lot to handle while driving, it is a straightforward system that's easy to understand once you use it a time or two. As a safety feature, cruise control systems are designed to be automatically disengaged as soon as the brake pedal is pressed. After you finish pressing the brake, a RES or RESUME button will reactivate the system and automatically accelerate back to the cruising speed.

How to use cruise control safely

While cruise control certainly makes driving a much less harrowing experience, it should be used safely so that you don’t cause any accidents or break any laws. Let’s take a look at a few tips to ensure the safe use of the system.

  • Be ready to brake - people will sometimes get lost in the moment of using cruise control and start to act as if they’re driving a self-driving car that will do everything for them. In most cases, the cruise control will not adjust for hazards in the roadway, and you should always be in control of the vehicle and be paying attention.  
  • Don’t use it when you’re tired - if you’re already tired or suffer from driver fatigue, you should not use cruise control. If either of these things is true, cruise control only makes it easier for you to start to drift off or pay less attention, which can be catastrophic for yourself or those around you.  
  • Don’t use it in slippery conditions - these types of situations — including roads covered in snow, ice, or rain — make traction loss significantly more likely than during dry conditions. If the vehicle starts to lose any traction, cruise control will often still try to maintain the speed, and it could lead to loss of control of the car.