Adaptive Cruise Control (ACC) is like regular cruise control, but smarter—and when you’re towing, that “smart” can turn into a problem.
How Adaptive Cruise Control works
1. It constantly watches traffic ahead
ACC uses:
- Radar (usually behind the front grille)
- Sometimes cameras
to measure the distance and speed of the vehicle in front of you.
2. You set the speed and following distance
You choose:
- A maximum speed
- A time gap (e.g. 1–4 seconds behind the vehicle ahead)
The system then automatically:
- Accelerates if the road clears
- Slows down if a vehicle moves into your lane
- Matches the speed of slower traffic
Some systems can brake all the way to a stop and pull away again in traffic.
3. It controls the throttle and brakes for you
Unlike normal cruise control, ACC actively:
- Reduces engine power
- Applies the brakes when needed
This is where towing becomes risky.
Why Adaptive Cruise Control should NOT be used when towing
1. Braking distances are much longer when towing
When you’re towing:
- Your vehicle weighs significantly more
- The trailer adds momentum
- Trailer brakes may react more slowly than vehicle brakes
ACC does not calculate trailer weight or braking performance.
It may brake too late or too gently, especially at highway speeds.
2. ACC can apply sudden braking
ACC sometimes brakes quickly if:
- A vehicle cuts in front
- Traffic slows unexpectedly
With a trailer, sudden braking can cause:
- Trailer sway
- Jackknifing
- Loss of control
Smooth, early braking is critical when towing—ACC isn’t designed for that.
3. It doesn’t “see” your trailer
ACC only monitors what’s ahead, not:
- Trailer length
- Trailer brakes
- Load balance
- Road gradient effects on the trailer
The system assumes a solo vehicle, not a vehicle pulling extra mass.
4. Downhill control is unsafe
On downhill sections:
- ACC may rely heavily on vehicle brakes
- It may not downshift early enough
- Trailer brakes can overheat
Experienced towing requires manual gear selection and engine braking, not automation.
5. Manufacturers explicitly warn against it
Most vehicle manufacturers state in the owner’s manual:
- Do not use adaptive cruise control while towing
- Some vehicles automatically disable ACC when trailer wiring is detected
That’s a big clue it’s not just “advice”—it’s a safety limitation.
What to use instead when towing
- Standard cruise control (only on flat roads, light traffic)
- Or better: manual speed control
- Select lower gears on hills
- Increase the following distance significantly
- Brake early and gently
Bottom line
Adaptive Cruise Control is designed for solo vehicles in normal traffic.
When towing, it:
- Can’t account for extra weight
- Can brake too late or too sharply
- Increases the risk of trailer instability
So when you’re towing—turn ACC off and stay in full control.
References:
National Highway Traffic Safety Administration (NHTSA), Vehicle-to-Vehicle Technologies and Adaptive Cruise Control, U.S. Department of Transportation, Washington, DC, 2023.
Insurance Institute for Highway Safety (IIHS), Advanced Driver Assistance Systems: Adaptive Cruise Control, IIHS, Arlington, VA, 2024.
Bosch Mobility, Adaptive Cruise Control (ACC): Driver Assistance Systems, Bosch GmbH, Stuttgart, 2023.
Ford Motor Company, Ford Owner’s Manual: Towing and Adaptive Cruise Control, Ford Motor Company, Dearborn, MI, 2022.
Volkswagen AG, Driver Assistance Systems – Adaptive Cruise Control (ACC) and Trailer Operation, Volkswagen Owner’s Manual, Wolfsburg, 2021.
Society of Automotive Engineers (SAE International), Human Factors and Automation Limitations in Driver Assistance Systems, SAE Technical Paper Series, Warrendale, PA, 2020.
Caravan and Motorhome Club, Towing Safety: Use of Cruise Control and Driver Assistance Systems, Camc.com, UK, 2023.
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