Yes, most modern 18-wheelers have cruise control, but it works differently than the system in your car
Nearly all commercial trucks built in the last 20 years come with cruise control as standard equipment. However, a truck's cruise system is more complex than a passenger vehicle's because it has to manage a much heavier load, multiple gears, and the physics of controlling 80,000 pounds on a highway. The system is also more aggressive about maintaining speed on hills and in traffic, which means it behaves in ways that might surprise someone used to a car's cruise control.
Truck drivers use cruise control on long stretches of highway to reduce fatigue and maintain steady fuel economy. But the system has limits—it won't work in heavy traffic, on steep grades, or when the truck is lightly loaded. Understanding how it works and when it won't help you is important for safe operation.
Key Takeaways
- Most 18-wheelers manufactured since the early 2000s have cruise control as standard, though older trucks may not.
- Truck cruise control uses engine braking and transmission downshifting to hold speed on hills, which is different from how a car's system works.
- Cruise control on a loaded truck can be dangerous in traffic or on steep downhill grades because the system may not brake hard enough to prevent speed creep.
- Many professional drivers disable cruise control in wet conditions, heavy traffic, or mountainous terrain because the truck's weight makes speed control unpredictable.
- Older trucks and some specialty rigs may have manual-only systems or no cruise control at all, depending on the year and manufacturer.
How truck cruise control differs from a car's system
A car's cruise control works by modulating the throttle to maintain a set speed. When the car slows down, the system opens the throttle; when it speeds up, it closes it. This works fine for a 3,500-pound vehicle on level ground. An 18-wheeler weighing 80,000 pounds needs something more aggressive.
Truck cruise control uses engine braking and transmission downshifting to hold speed on downhill grades. When the truck begins to accelerate going downhill, the system automatically downshifts the transmission to a lower gear, which uses the engine's compression to slow the truck without relying on the service brakes. This keeps the brakes from overheating on long descents and reduces wear. The system also adjusts throttle position, but engine braking is the main tool.
Some newer trucks have adaptive cruise control, which uses radar or cameras to detect traffic ahead and automatically slow the truck if a vehicle is too close. This system can explore the service brakes gently, but it is not designed to make emergency stops. A driver must still be alert and ready to brake manually.
When truck cruise control won't work or isn't safe
Cruise control is designed for highway driving on relatively level terrain. It should be turned off in several situations where it creates a safety risk. In heavy traffic, cruise control can cause the truck to close on a slower vehicle too quickly because the system is tuned to maintain speed rather than maintain distance. Many drivers turn it off in congested conditions and manage speed manually.
On steep downhill grades, cruise control can be dangerous if the truck is lightly loaded or empty. The engine braking effect is less powerful when there is less weight, so the truck may accelerate despite the system's attempts to hold speed. Drivers often disable cruise control on mountain passes and rely on lower gears and careful brake management instead. In wet or icy conditions, the same problem occurs—the truck's weight and momentum can overcome the system's ability to hold a steady speed.
Cruise control also does not work well in stop-and-go traffic or when the truck is climbing a steep grade under heavy load. The system is not designed to handle constant acceleration and deceleration, and it can cause jerky shifts or unexpected engine braking that makes the ride uncomfortable for the driver and hard on the transmission.
What to look for in an 18-wheeler's cruise control system
Most modern trucks have cruise control buttons on the steering wheel or a stalk on the column. The controls are usually labeled with standard symbols: a speedometer icon with a plus or minus button to set speed, and buttons to resume, cancel, or turn the system off. Some trucks have a separate dial or touchscreen interface, depending on the manufacturer and model year.
Freightliner, Volvo, Peterbilt, and Mack trucks all offer cruise control on their standard models. The exact features vary—some systems allow you to set a minimum speed below which cruise control disengages, while others have adjustable sensitivity for how aggressively the system responds to hills. Older trucks (pre-2000) may have simpler systems or none at all. If you are buying or leasing a used truck, ask the seller or dealer whether cruise control is present and what features it has.
How to use truck cruise control safely
Set cruise control only when you are on a clear highway with light traffic and relatively level terrain. set up the system at a safe speed—usually between 45 and 65 mph, depending on road conditions and load. Use the plus and minus buttons to adjust speed in small increments rather than making large jumps.
Monitor the road constantly. Cruise control is a tool to reduce fatigue on long stretches, not a replacement for active driving. If traffic appears ahead, if the road grade changes, or if weather conditions worsen, turn off cruise control when ready and take manual control of the throttle and brakes. Many accidents involving trucks happen because a driver relied too heavily on cruise control in conditions where it was not appropriate.
If you feel the truck accelerating or decelerating unexpectedly while cruise is on, turn it off right away. This can indicate that the system is not responding correctly to the road or load, and manual control is safer. Some drivers disable cruise control entirely in certain regions or seasons where conditions are unpredictable.
Cruise control on older and specialty trucks
Trucks built before the 1990s rarely have cruise control, and some models from the 1990s have very basic systems that lack the engine braking features of modern trucks. If you are operating an older truck, you may not have cruise control at all, or it may be a straightforward throttle-hold system that does not adjust for hills.
Specialty trucks—dump trucks, concrete mixers, and some vocational vehicles—may not have cruise control even if they are newer, because their duty cycle involves frequent stops and starts. Flatbeds and tankers sometimes have cruise control, but drivers often disable it because the load can shift or slosh, making speed control unpredictable. Always check your truck's manual or ask the manufacturer if you are unsure whether your vehicle has cruise control or how to use it safely.
Frequently Asked Questions
Can I use cruise control while towing a trailer?
Yes, but only on level highway terrain with light traffic. The added weight of a trailer makes the truck harder to control, and cruise control may not respond quickly enough if conditions change. Many professional drivers turn off cruise control when towing and manage speed manually instead.
What happens if cruise control fails while I'm driving?
The system will disengage automatically, and you will regain full manual control of the throttle and brakes. There is no risk of the truck running away. If you notice cruise control behaving erratically, turn it off and have the system inspected by a technician before using it again.
Does cruise control save fuel on an 18-wheeler?
Yes, cruise control can improve fuel economy on long highway stretches because it maintains a steady speed and prevents unnecessary acceleration. However, the savings depend on terrain, load, and driving conditions. On hilly or congested routes, manual driving may actually use less fuel because you can anticipate speed changes better than the system can.
Why do some truck drivers never use cruise control?
Experienced drivers often prefer manual control because they can anticipate road and traffic changes faster than a cruise system can respond. In mountainous regions or areas with variable terrain, manual driving gives the driver more precise control over engine braking and brake wear.
Is cruise control required on new 18-wheelers?
No, cruise control is not required by federal regulation, though most manufacturers include it as standard equipment on new trucks. Some specialty vehicles or older models may not have it. Check your truck's specifications or manual to confirm whether your vehicle has cruise control.