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Cruise control

i was listening to some people talk about gas prices and one person was talkig about how they use cruise control and then another chimed in and said that using cruise control on a hill is bad for a car. is there any truth to this

No. Roads Are Littered With Hills.

Understand How Cruise Control Works. It Moves The Engine’s Throttle For You In Order To Maintain Desired Speed So That You Don’t Have To Use Your Foot. That’s It. How Is That Bad For A Car ?

You and your friend need to find a mechanic or mechanically inclined friend who can pop the hood on a car and demonstrate what I’m talking about. It’s not rocket science.


Nothing wrong with cruise, it just does automatically what you’re going to do with you foot anyway, however…

Depending on what you’re doing (for example, a truck and you’re towing or you’ve loaded down the car) cruise control can make the engine work harder on hills, when you really should just slow down and/or use a lower gear. This all depends on the vehicle, the hill, and the load.

Had this happen with a borrowed Escape (underpowered). Someone else was telling me it was chewing through gas while he was moving and driving back and forth. I went with him on one trip, and the thing was downshifting 2 gears while trying to maintain 70 MPH. He stopped with the cruise, and his mileage got immediately better…although the trips got a bit longer.

The friend who said this is “bad” for the car – what does he recommend? Canceling cruise control when approaching a hill? Re-engaging it at the top?

Just assume this person has no idea what he is talking about. You won’t go far wrong.

Hill or no hill, a knowledgable dedicated driver can be safer and get better mileage than using the cruse control.  However it means a lot of work for minimal improvements and can result in making the driver tired and causing them do less well than curse.

Frankly the difference is generally not worth the bother or worry.

Cruise control is a great tool and every time I’m on a limited access highway I wish more people would use it. Nothing makes a mess faster than a bunch of people who can’t figure out whether they’re doing 80 or 70 or 60 or what. Lots of people just sort of do any of the above, seemingly at whim, and it does make a mess. So you should use your cruise control.

It is mostly for highway use. Using it around town is loopy.

What one does need to keep in mind is that cruise control mechanisms are not very “smart” since they can’t see the road ahead - they can only respond to what is happening now. Your best bet for fuel economy is to maintain a consistent speed at minimium throttle position. For hills, the best way to do that is to accelerate mildly as you’re hitting the hill so as not to lose momentum. Most cruise control devices will be a little behind the game (some are better than others) and allow you to lose momentum. They then end up popping the throttle open fairly wide, often leading to downshifting (sometimes necessary anyway, but not always). When this happens you are generally worse off on fuel economy.

I just act as a “cruise control assist” and will sometimes proactively lay on the throttle a bit if I see something that my cruise control will not handle well. Sometimes you have to do the opposite as well. Many cruise control mechanisms are not only a little slow to pick up on the loss of momentum at the bottom of a hill, but are also a little dumb as you top out on the hill. The one on my daily driver is like this and will shoot me over the top of a hill sometimes as much as 5mph over my set speed. So you’ll find me nudging the throttle at the bottom of a hill and tapping the coast at the top of a hill.

For particularly rolling hills roadways it begins to become more hassle than its worth so there is a difference between a hill once in a while and a road that has extreme grades and/or lots of them.

Cruise control doesn’t mean that you turn your brain off and stop paying attention, and it certainly doesn’t mean that you are somehow not still in control.

Don’t use it in bad weather - heavy rain, snow etc.

Good Exposition, But What About " . . . using cruise control on a hill is bad for a car. is there any truth to this [?]" That’s The Topic For Which tums239 Wanted Your Opinion.


I was assuming that the issue was about fuel economy since the opening line had the discussion being spurred by fuel prices. So I talked about fuel economy.

But, if you must enforce your idea of what the OP wanted an opinion about: the car itself could care less.

Although I agree with what everyone says about it not harming the car, I can see where there might be some truth to this.

Suppose you are driving a heavy rig, or a loaded pick-up truck pulling a loaded trailer. You will actually save gas by letting your speed decrease as you go up the hill, which cruise control won’t let you do. Then you regain that speed going down the hill. This manual operation of the throttle would save you fuel, and prevent an automatic transmission from downshifting. If you leave the cruise control on, the automatic transmission will downshift, and the engine will be strained trying to maintain the speed at which the cruise control is set.

If you are just driving a normal car, and it isn’t loaded with cargo to its capacity, you should just leave the cruise control on and let it do its thing.

True…but I think cigroller and I covered that.

However, still, it’s not bad for the car/truck/rig in any event.

I guess you don’t think pushing the engine while going uphill with a heavy load can harm an engine, or make the engine and transmission overheat, but having driven my fair share of tractor trailers and RVs, I’ve seen it myself. You notice it particularly when you have a temperature gauge on the dashboard, or when you feel the heat coming off the transmission when you pop the hood.

Not really, no…the systems are designed to disengage when it hits 20 below the set limit just to prevent that damage. Maybe the system you had was malfunctioning? I guess I can’t assume that all systems will work properly, nor the same.

I have to assume that a driver can tell when his engine is screaming and straining. If that happens, it’s just time to downshift, and slow down - lower gears, slower climb.