Car Advice

Reader question: should I cancel cruise control downhill?

This week we received a question from a reader about whether they should cancel cruise control when driving down a hill.

G’day, I’ve only just started driving a car with cruise control, and I want to know if I am harming my car by cancelling cruise control when going down a long steep hill and coasting instead of letting the car automatically rev up in a lower gear to stop going over the set limit. I do this and find that on steep gradients the car will coast down hill at the same speed and when I get to the bottom I flick cruise reset. I only do this when there is no slower cars in front of me.

Hi there,
You’re best off leaving the car to do its thing. Modern automatics sense gradients and automatically select lower gears. This is done so the brakes don’t overheat, and it’s easier to control the car if it has a lower gear. The cruise control is only replicating what a human drive would do. Yes, revs may be a bit higher, but that’s fine.
 
I’m a bit confused by the statement that it coasts down the hill at the same speed… if the gradient is steep the car will speed up. However, most steep gradients also have significant corners, so aren’t suitable for cruise control. There are some freeways that are quite steep, for example the approach into Adelaide.
 
Another point is that not all cruise control systems stop the vehicle exceeding the set speed, most permit overruns. In that case, you’ll need to take control yourself either by braking gently or selecting a lower gear, both of which will deactivate cruise control.
 

4 Comments

  1. Andrew Riles
    July 8, 2016 at 8:32 am — Reply

    Interesting question….I don’t think I have used a cruise control system yet that maintains my preset speed on downhill sections, so often have to brake lightly or manually downshift to stay within the safe and/or legal limit for the road…..

  2. John Johny
    July 8, 2016 at 11:58 am — Reply

    Both my i30 and RAV4 have cruise control and I leave them on going downhill. Both of them will go over the set speed even if they are in lower gear. Nothing to worry about.

  3. 1250
    July 8, 2016 at 6:26 pm — Reply

    Yep l had one fitted on my trident (Man/DE 3.2 it’s a fly by wire unit ,very good at flat speed and like the others ,have to brake going down hills ,
    It’s has returned a very good fuel saving and money well spent and a fortune in NO speeding fines

  4. Benjamin Roach
    August 26, 2017 at 5:04 pm — Reply

    Having cruise control give out down hill is massively annoying. For anyone else that cares and wants a car that has a properly functioning cruise control, my Audi A3 never had a problem retaining set speed down hill. I now have a Hyundai i30…. disappointing. Having a car speed up relatively randomly couldn’t possibly be a safety feature. This will be something I check before committing to a car in future.

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Robert Pepper

Robert Pepper

Robert Pepper is a motoring journalist, offroad driver trainer and photographer interested in anything with wings, sails or wheels. He is the author of four books on offroading, and owns a modified Ford Ranger PX which he uses for offroad touring. His other car is a Toyota 86 which exists purely to drive in circles on racetracks, and that's when he isn't racing his Nissan Pulsar. Visit his website: www.l2sfbc.com or follow him on Facebook https://www.facebook.com/RobertPepperJourno/ or buy his new ebook!