Fuel Economy - Cruise Control

[wimorrison]

Driving to work this morning I did not use the cruise control, which I normally set at 75 (ish) and upon arriving at work I noticed that my consumption had improved by 0.1 MPG.

Not a lot, I hear you say but it made me recall the programme where Clarkson tried to drive from London to Edinburgh on a single tank and one of the things he said was that it was more effeicient to use manual speed control that automatic cruise control.

Has anyone experience of comparitive studies or personal experience to prove/disprove the theory?

[mu71rd]

i had been wondering this, and was discussing it with some friends on a trip this weekend.

I think if you are adamant you want to maintain a steady speed then cruise is best for MPG because it will choose the lowest rev/gear combo to maintain the exact speed.

But my friend told me he drove trying to keep a constant mpg on the instantaneous reading. ie - if he's going flat he aims (in his case) for 50mpg. If going down hill it means he speeds up, and uphill he slows down. Net speed is probably still the same, although it requires more concentration and does involve speed changes regularly.

he basically just keeps his foot in the same place the whole time, and let the car speed up or slow down according to the incline.

apparently gets much better mpg as a result.

[adambsmith]

A long time ago, we had a PT Cruiser Diesel which suffered horrendous MPG when using cruise - far better just using one's foot on that model.

[Mislovic]

i can't speak for all cars, but.. for the few cars which i had, it is more fuel efficient to manually adjust your throttle.

when I switch to instantenous fuel consumption, I found that most cars are still applying a bit of throttle, on roads which I would normally release the accelerator.

the difference is about 0.5 to 1ltr/100km, so, for the convenience, i would still use the cruise control for long distance driving.

[Bernard333]

Cruise control has been one function I have made sure I had on every car since 1995 because doing the high mileages I was clocking up through work the circulation in my right leg was becoming affected due to the long time spent resting on the accelerator so it became essential for me and I think without it I would not have been able to do the job . Fuel economy was also very important to me because the way my company reimbursed costs was based on mileage , on a typical 500 mile trip that meant I would either be in profit or making a loss which could be up to £20 so I would do everything possible to stay in profit and have kept exact records of fuel cosumption on every car I have driven . Cruise control uses more fuel in most driving situations my estimate is approx 3 to 4% but it depends on how the car is driven and the number of hills on the journey .

[wimorrison]

My 0.1mpg improvement became 0.2mpg improvement tonight when I drove home using the manual control rather than cruise control - quite a way to go to get the 3-4% suggested as possible, but I think that the argument is sound and I will use the mk1 human foot rather than the cruise control

[tem]

Cruise Control - Is a positive aid for me.

I do a lot of long distance driving and without the Cruise Control, I would find the journeys, exausting.

Just recently, returned from a round trip, from the North of Scotland, to Northern Italy (Sud Tyrol) and with Cruise Control (used, where ever possible), I averaged 39.8 mpg.

To gain a few extra mpg, with foot control (if this is possible), is not worth the effort and discomfort.

My views.

tem.

[Vecais]

Cruise Control is an essential driving aid for me to help avoid speeding tickets.

The Volvo Cruise Control is the best I have had for a couple of reasons, firstly the digital speed setting number is much more precise than the usual guess of a point on the speedo and secondly the speed control works down to about 30kph, great for passing roadworks or such.

Who cares about minor savings in fuel consumption. The value of one speeding ticket here will buy about 4-5 tank fills of fuel.

[watson-lfc]

I recently went down to donington park to watch a drifting event, 3 of us in the car and sat with cruise control on all the way there at around 80-85mph. used 3 quartes of tank to do around 200 mile!! On the way back i didn't use the cruise control and sat at about 90 and it used around half a tank. Thats a substantial difference isn't it?!

[XC60 N Yorks]

For what its worth, I have found the XC60 cruise control less fuel thirsty than any car I have previously owned, including "Er in doors" XTrail. But I agree foot control always wins.

If fuel economy is your thing, can I suggest keeping your XC60 very clean.

For the last 5 years I have done a routine weekend 150 mile round trip (same journey). While at my destination I have the opportunity to get the car hand washed for £6, and I always fill up on fuel as its much cheaper than where I live. A couple of months after I got the XC60 (had it 8 months now), I realised to my disbelief, that when I didn’t wash the car I used about 15-20% more fuel on the way home v when I have the car washed. Essentially the hand wash pays for itself on my journey home, and I have a shinny car for the start of the week.

Now I wash the car before any long journey.