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[TheBoy]

I have done some fairly extensive testing in my 3.0l on this, and cruise does use more fuel.

Not tried with the 3.2, as too many 'tards on the roads now in the UK to make much use of cruise.

[05omegav6]

Came in useful on the truck what which I drove from Shoreham to Ashford and back 56mph all the way there, and 56mph all the way back

[Entwood]

Cruise can save you money .... and not just on speeding fines !! 

I agree that IF you are able to sit and control the speed accurately using the throttle you will get better mpg than using cruise, which as said is a little harsh at times.... however, if - like me - the tendency when not using cruise is to slowly speed up as the car is so responsive and fun to drive, then the mpg will be worse because quite simply .. the faster you go the more fuel you use ..

[2woody]

using cruise will probably cost you 5 to 10% over doing it the "normal" manual way, more if you aim to drive economically.

[VXL V6]

Well Not much opportunity to use cruise on my Journey this Afternoon - Worcester to Hastings, but from a full tank of fuel last night (at home - Solihull) I have done 240 miles and have a range of 494 miles.... 

[Terbs]

Forgive my ignorance

But...with my V6 (2.5 or 2.6) irrespective of the comparison against each other.....if I set cruise control at 30mph, you are saying I would use less petrol than setting cruise at 60mph
I know the logical answer is yes, but I was led to believe that with these type of engines, a higher speed was more economical. (speed within sensible parameters, obviously)

[Entwood]

Forgive my ignorance

But...with my V6 (2.5 or 2.6) irrespective of the comparison against each other.....if I set cruise control at 30mph, you are saying I would use less petrol than setting cruise at 60mph
I know the logical answer is yes, but I was led to believe that with these type of engines, a higher speed was more economical. (speed within sensible parameters, obviously)

30 / 60 are too far apart to use as comparisons, as the car would not be in the same gear for a start !! At 30 you will use more fuel than at 60 for sure .. due to gearing !!

A better comparison is 60 / 80 ... air resistance (drag) increases in proportion to the square of the speed .. so if we make up a few units .. drag at 60 = 3600 units, drag at 80 = 6400 units ...  the drag has almost doubled for a 20 mph increase... so the amount of energy needed to overcome the drag has also almost doubled !! That energy can only come from extra fuel burned.

If cruise keeps you at 60 you use less fuel than if manual driving starts to edge towards 80 ..

[henryd]

As government fuel figures centre on the 56mph reading that is where most cars are set up to be at there most fuel efficient.

[TheBoy]

As government fuel figures centre on the 56mph reading that is where most cars are set up to be at there most fuel efficient.

Probably more 90kph, as the Euro market is more important. Oh yeah, thats 56mph

[Terbs]

Thanks fellas....most enlightening
Entwood....sit down mate, and take a pill

[plym ian]

The trouble with cruise is that if you knock it off for whatever reason, it's too numb to accelerate gently till it reaches the previous speed.

How do you get it to 'resume'? The manual talks about it, but I've never been able to get that to work in my car.. it appears all I can do is 'set current speed as cruise', 'cancel cruise' or when cruise is active speed up/slow down..

With cruise cancelled, the "slow down" button will resume the last cruise control speed selected. You need to be doing around 20MPH or more for it to kick in from memory.

I'll try that again next time I'm on the motorway  I'm sure that's what I was doing.. or maybe I was pressing the 'increase speed' button 

don't do what I did, on motorway cruise on at 70mph came off motorway got to top of slip road came off brake to pull out as was clear whent to indicate and caught resume button. brown pants time as car was at 30mph trying to accelerate to 70mph again