Cruise for MPG

[Rick101]

I've seen several times here and elsewhere people professing the benefits of cruise control for maximising MPG.

Surely you can get better economy by using advanced driving techniques and planning ahead. I'm no expert but I can certainly achieve better figures by driving carefully.

[trashbat]

It depends how good you are at self-control!

Cruise is much better than I am at maintaining a low cruise speed, e.g. 65mph, whereas without it I get bored and speed up, usually averaging low 70s. That 65mph long distance cruise is how I got my best ever economy out of my car.

There are lots of reasons and circumstances in which it's worse or costs fuel, too, of course.

[martine]

I've never tried it but I imagine cruise control would be great for mpg on a motorway. On other roads though I think you'd be forever overriding it and of course cruise control can't make use of acceleration sense - so I reckon an alert, 'advanced' driver would do better.

The downside of cruise control on a motorway are those times when you see someone inching past a slower vehicle, causing a tailback (and frustration) - I keep thinking: "for goodness sake just put your foot down and get out of the way" but I usually resist the temptation to close the gap in effort to 'push' them along.

Like any in-car tech there's a time and place I guess but the more the driver relies on it, they less 'engaged' they are?

[waremark]

I use CC regularly. It does not reduce my engagement. I hope an Advanced Driver would use CC in an advanced way.

[jcochrane]

I use CC regularly. It does not reduce my engagement. I hope an Advanced Driver would use CC in an advanced way.

I also use CC for example on motorways or Dual carriageways where speeds are fairly constant or traffic fairly light. In my view one has to be more attentive when on CC. The trap is allowing concentration to drop.

In answer to martine where I need to slow I will switch off CC using acceleration sense to judge when to turn it off and then usually accelerating again to cruise speed and switch it back on. I could and sometimes just switch it back on depending on how much speed has dropped if too much speed has dropped the re-acceleration rate may be more than I want for smoothness. For overtakes my CC will allow me to accelerate and if I then lift off the car goes back to the set CC speed.

[waremark]

And I think the background point is that it is more economical to maintain an accurate constant speed than to make frequent minor adjustments around the same speed. Apparently.

[Horse]

It depends how good you are at self-control!

Cruise is much better than I am at maintaining a low cruise speed, e.g. 65mph, whereas without it I get bored and speed up, usually averaging low 70s. That 65mph long distance cruise is how I got my best ever economy out of my car.

There are lots of reasons and circumstances in which it's worse or costs fuel, too, of course.

Yup, that.

The m-way I regularly use is M4 J13-10 and, of that, J13-12 is hardly flat (ish). Since using CC to maintain constant speed would adversely affect fuel consumption, I'll often knock the speed down a tad then back up for the downhill and flatter sections.

However, I choose my 'set' speed according to other traffic, such as HGVs, as it's often easier to'blend' in L1 rather than travel at a slightly higher preferred speed and have to overtake either by speeding up or staying slow relative to L2 traffic approaching at higher speed.

[TheInsanity1234]

In answer to martine where I need to slow I will switch off CC using acceleration sense to judge when to turn it off and then usually accelerating again to cruise speed and switch it back on. I could and sometimes just switch it back on depending on how much speed has dropped if too much speed has dropped the re-acceleration rate may be more than I want for smoothness. For overtakes my CC will allow me to accelerate and if I then lift off the car goes back to the set CC speed.

Unfortunately, my dear father is not anything like this.

He sticks CC on, and attempts to go as long as possible without prodding the brakes - leading to some occasionally unnerving overtakes where he ends up less than a car length from the car in front before moving out to overtake, because he doesn't want to deactivate CC.

When he does have to deactivate CC, he does it by prodding the brakes, which means it's often the case where he leaves it to the last minute, then brakes sharply, whereas if he just cancels it using the button, then the car would slowly drop some speed, thus making many manoeuvres much smoother.

I'm not sure he's heard of smoothness when it comes to driving a car though.

[TripleS]

About six years ago I accidentally (1) covered 980 miles on one tankful (2) of diesel, so I reckoned that 1000 miles on a tankful should be doable if I set my stall out right. Well now we've done it, and rather well, too.

Having recently obtained a nice little motor for Eileen, attention has now turned to finding a decent MR2 Mark 2, Rev. 3 or later, for our Mike. These cars are now about 20 years old, and it's not easy finding a good one, so we've been getting around a bit this last week or so.

Last Saturday we had a trip from Whitby to Manchester, then on to Stafford, then Nottingham and back to Whitby: 394 miles averaging 62.8 mpg. We filled up at the start of that trip.

Last Sunday we went to Durham and back: 122 miles averaging 58.9 mpg.

Yesterday we went from Whitby to Waltham Cross and back: 495 miles averaging 68.9 mpg. Now then; I am accustomed to old CUBby putting up some very good economy performances, but even I was astounded to find that the trip yesterday (after zeroing the trip computer at the start of the journey) not only averaged 68.9 for the day, but it showed 72.5 at the point where we arrived at the traffic congestion around Enfield. That produced a bit of a setback, but it was only to be expected.

The latest tankful has therefore yielded about 1100 miles, including a bit of local usage during the week, so I'm quite chuffed with that: and the car does not have cruise control! What it does have is a good engine, now quite nicely run in after 190,000 miles, and of course a highly skilled eco-driver.

(1) 'Accidentally' in that I wasn't really trying to get good economy.
(2) Nominal tank capacity is supposedly 70 litres, but it actually holds quite a bit more than that.

OK, there you go; I just thought you might be interested in that; but maybe not. Anyhow you've got it, so there!

Oh, one final thing: this was on BP normal diesel. It seems to be good stuff.

Best wishes all,
Dave - advanced eco-bore.

[superplum]

OK, there you go; I just thought you might be interested in that; but maybe not. Anyhow you've got it, so there!

Oh, one final thing: this was on BP normal diesel. It seems to be good stuff.

Best wishes all,
Dave - advanced eco-bore.

and the car is...?

[Silk]

OK, there you go; I just thought you might be interested in that; but maybe not. Anyhow you've got it, so there!

Oh, one final thing: this was on BP normal diesel. It seems to be good stuff.

Best wishes all,
Dave - advanced eco-bore.

and the car is...?

Some French crap.

[TripleS]

OK, there you go; I just thought you might be interested in that; but maybe not. Anyhow you've got it, so there!

Oh, one final thing: this was on BP normal diesel. It seems to be good stuff.

Best wishes all,
Dave - advanced eco-bore.

and the car is...?

Some French crap.

Yes, very similar to the French crap that Silk was blundering about in a few years ago, and about which he was fairly complimentary at the time!

Mine is a Pug 406 HDi, now 14 years old, with 90 bhp, and he had the 110 bhp version of the same model. I remember him saying "...they do go well." I expect the old bu99er has forgotten that. He spend too much time trying to wind up the good folks 'ere.

Best wishes all,
Dave.

[GJD]

And I think the background point is that it is more economical to maintain an accurate constant speed than to make frequent minor adjustments around the same speed. Apparently.

While that may be true if the road is flat, I'm not sure it's still true once you start going up and down a few hills.

[TheInsanity1234]

And I think the background point is that it is more economical to maintain an accurate constant speed than to make frequent minor adjustments around the same speed. Apparently.

While that may be true if the road is flat, I'm not sure it's still true once you start going up and down a few hills.

In my eyes, when you're driving on the motorway and there are a few gradients, it's probably more economical to build up speed going downhill, and be a bit more light-footed whilst going up hill.

This may cause the speed of your vehicle to vary between 60 and 80 (depending on car blah blah), but someone with CC switched on at 70 would use more fuel as the car would open the throttle to maintain 70 going uphill, and close off the throttle to maintain 70 going downhill, resulting in the car gaining no extra momentum on the downhill bits that can be burnt off on the uphill bits.

[Horse]

And I think the background point is that it is more economical to maintain an accurate constant speed than to make frequent minor adjustments around the same speed. Apparently.

While that may be true if the road is flat, I'm not sure it's still true once you start going up and down a few hills.

In my eyes, when you're driving on the motorway and there are a few gradients, it's probably more economical to build up speed going downhill, and be a bit more light-footed whilst going up hill.

This may cause the speed of your vehicle to vary between 60 and 80 (depending on car blah blah), but someone with CC switched on at 70 would use more fuel as the car would open the throttle to maintain 70 going uphill, and close off the throttle to maintain 70 going downhill, resulting in the car gaining no extra momentum on the downhill bits that can be burnt off on the uphill bits.

As I posted, ^ up there, somewhere . . .

The m-way I regularly use is M4 J13-10 and, of that, J13-12 is hardly flat (ish). Since using CC to maintain constant speed would adversely affect fuel consumption, I'll often knock the speed down a tad then back up for the downhill and flatter sections.

My fuel consumption varies enormously depending on factors such as other traffic and how bored/late I am.

Worst is probably low-50s, best has been 74.5. That was achieved one evening when I was low on fuel but couldn't be bothered to stop and fill up (which would have been at service area extortionate cost too!), so drove slower than usual and did everything to avoid using the brakes but without causing tailbacks (it was early evening, so the 'rush' was largely over). Unfortunately, H's stable is on top of a steep hill, otherwise it would have been even better. Amusingly, the 'predicted range' was going up for much of the journey!