Cruise Control Question

[TREMAiNE]

I've been using cruise control a lot recently, mainly because it relieves a lot of the temptation of speeding.

Over the years, I've heard many rumors about cruise control, most of which are probably just bullst, but just in case, I was wondering if someone could clarify for me -

Is it true that having CC switched on but not actually activated (if that makes sense) can actually damage the system?

Is repeatedly changing your speed with CC switched on bad for the system, should you turn the system off before adjusting your speed dramatically?

Does CC actually get you better MPG (It makes sense that it does), and if so will the difference actually make a difference between fill ups or is it one of those "You'll end up saving £50 a year" sort of thing?

Sorry for the novice questions, I'm just not particularly used to sitting back, relaxing and reading a book on the way to work (That was a joke... before the inevitable comments occur)!

[pti]

IME cruise actually reduces the mpg as it fails to read the road. For example, going downhill (into a valley) you (the driver) may increase speed slightly so that you use less gas on the way back up. Cruise remains constant regardless of topography.

No idea about that other questions but I definitely wouldn't have though so. Willing to be proved wrong though.

[Superhoop]

Leaving CC on won't damage the system, and changing speed using the buttons whenever you feel the need won't either.

As for fuel economy, most of the cars I've had, it does manage to give slightly better economy, but it's minimal, and of course depends on your normal driving style.

I use it all the time, and my current car has radar cruise, which is even better still (most of the time!!)

[RB Will]

I wouldnt worry about any of that. I certainly have not done any harm over the years using it like you say.

I find I can get slightly better MPG with my own foot rather than CC but the effort it takes is not worth the money saving.

[Prizam]

At night, using CC to maintain a slower speed does give better economy.

During the day when you are constantly on and off the CC system, slowing down and speeding up..... Not so much.

[mrmr96]

pti said:

IME cruise actually reduces the mpg as it fails to read the road. For example, going downhill (into a valley) you (the driver) may increase speed slightly so that you use less gas on the way back up. Cruise remains constant regardless of topography.

This is potentially offset to an extent by it being able to maintain a solid cruise speed on the flat sections, rather than burning extra then coasting slightly as you'd do if you adjusted with your foot. (However again, there is some evidence that "burn and coast" can give very good economy in modern cars - but it's as annoying a f**k for all the other road users around you!)

[JimmyTheHand]

Cruise control, like a lot of thinks has changed a lot over the years - I suspect "potential damaged" comes from the old mechanical versions. If it is operated by buttons on steering wheel/stalks (as pretty much anything in last decade+ will be) then it will be a computer controlling the car. I can see using the buttons will be no different to using the throttle/gas pedal (especially on newer cars where neither connect to anything other than a computer).

One thing to watch though - some cruise controls will operate the brakes to keep speed down - which may chew through rear brake pads.

What I found cruise control did to improved economy - it removed the temptation to just keep edging up the speed on long motorway runs, instead when I overtake I can just take foot of pedal and drops back to speed set.

[mrmr96]

JimmyTheHand said:

One thing to watch though - some cruise controls will operate the brakes to keep speed down - which may chew through rear brake pads.

Mine doesn't use the brake, but it does have a cool feature on steepish motorway declines - it will actually drop out of top gear and into a lower gear to use engine braking if the speed drifts up too far on the down slope!

[David87]

Cruise control is something that I use all the time and miss if I drive a car without it. I'm yet to try the radar-guided version, which I suspect is quite strange at first! Random cruise control fact: the Renaultsport Clio 182's cruise control only operates at speeds of up to 126mph. Yes, I did have it set at that.