thanks again for all the comments

im currently getting about 360 miles from a full tank !!urban in the week abit of motorway at the weekends is that about right !!!!!!

A successful technique I have tried to reduce consumption on fast roads is accelerating up to 70mph (slowly so that the DSG does not drop below 7th gear) and then coasting (still in D) down to 50mph, this seems to use less fuel than a constant speed.

I would also add that I only do this when no-one is close behind as I imagine this would annoy anyone behind trying to drive steadily!

Also keep my tyres on the firm side 35-37 psi and use acceleration sense all the time (the IAM look ahead break less technique)

using this I have seen 49 mpg on long journeys.

A successful technique I have tried to reduce consumption on fast roads is accelerating up to 70mph (slowly so that the DSG does not drop below 7th gear) and then coasting (still in D) down to 50mph, this seems to use less fuel than a constant speed.

I would also add that I only do this when no-one is close behind as I imagine this would annoy anyone behind trying to drive steadily!

Also keep my tyres on the firm side 35-37 psi and use acceleration sense all the time (the IAM look ahead break less technique)

using this I have seen 49 mpg on long journeys.

Pulse and glide that is known as.

The theory behind it is that in the time that you are accelerating from 50-70 you are doing maybe 20-odd or 30-odd mpg then in the time that you glide back down to 50 you are using 0 fuel so you effectively double the economy that you got while accelerating as you spend half the time doing 30mpg and half the time doing infinite mpg.

If you have a manual I fine it useful to keep the instant MPG display up on the screen so you can see how the gear you are in is affecting economy. Sometimes the gear you think is not always the most economical and changing down can sometimes give you better economy.

Phil

Pulse and glide that is known as.

The theory behind it is that in the time that you are accelerating from 50-70 you are doing maybe 20-odd or 30-odd mpg then in the time that you glide back down to 50 you are using 0 fuel so you effectively double the economy that you got while accelerating as you spend half the time doing 30mpg and half the time doing infinite mpg.

If you have a manual I fine it useful to keep the instant MPG display up on the screen so you can see how the gear you are in is affecting economy. Sometimes the gear you think is not always the most economical and changing down can sometimes give you better economy.

Phil

Depends how important a few mpg is to you. Id rather sit with cruise control on at a constant 80mph indicated and get there quicker with less stress. Pulse and gliding between 50 and 70mph would serioulsy drop your average mph compared to cruising at a constant 70 or 80mph. I would imagine cruising puts less stress on the mechanical bits also so long term may not be so good.

Life is too short TBH to pulse and glide. I do enjoy driving economically in town and on back roads by reading the road ahead and minimising braking as you can still drive quickly when employing this technique but pulse and gliding just seems anal IMO.

If a hypermiler was doing pulse and glide they would accelerate up to about 90mph then back down to 50mph.

So 20mph either side of the speed limit. That would give you an average of 70mph and would give even bigger savings as you would be off the gas for quite a while as it slows back down to 50mph.

Phil

Take out the back seats, fit narrower tyres (check insurance), get smaller wing mirrors.

You'll get to a point where you'll be better off getting another car.

I could average 65mpg without too much trouble in a Clio diesel with 100hp. 86mpg was my record for a commute. Cost pennies to run. But it was a hateful, rattly, tinny box that I hated.

Id say seriously consider buying a diesel. Not as fun granted but much better on fuel in pretty much all conditions. Had a Fabia vRS estate and swapped it v recently for an Octavia Blackline estate as was getting sick of its more often than not less than 300 mile range and 31mph average

Anybody tried putting 98 octane in their tank?

It may be more expensive, but the MPG seems to drop - a better bang for your buck.

Also, be careful trying to use coasting to stretch yer miles per gallon - I believe it's illegal as you are required by law to be in control of the vehicle at all times. "Coasting" means that the engine is disengaged from the road wheels and the car will become unwieldy and difficult to nigh on impossible to keep under control at speed.

If a hypermiler was doing pulse and glide they would accelerate up to about 90mph then back down to 50mph.

So 20mph either side of the speed limit. That would give you an average of 70mph and would give even bigger savings as you would be off the gas for quite a while as it slows back down to 50mph.

Phil

Tsk tsk. 90mph. Seriously though would doing this not get tedious after 3 hours? Plus is it even possible on congested roads? Think you would get flashed a lot.

Also, be careful trying to use coasting to stretch yer miles per gallon - I believe it's illegal as you are required by law to be in control of the vehicle at all times. "Coasting" means that the engine is disengaged from the road wheels and the car will become unwieldy and difficult to nigh on impossible to keep under control at speed.

I would never recomend coasting out of gear... for a start it doesn't actually save fuel and still uses fuel whereas coasting in gear uses no fuel at all and you are still in control of the vehicle.

Phil

Use a sat nav to plan journeys. . . .

NEVER rely on a Satnav to plan your journey. I usually don't but on Sunday I was in a bit of a rush and left the road atlas at home and only had the Satnav. I was enroute to my cousins house happily traveling along a nice fast smooth dual carriageway when suddenly I was told to take the next exit, which was not one you can get out of once you have started along it. I was then directed along small country lanes, up hills and down dales, through floods and mud - all destroying any economy I might have built up - all to save about 2.5 miles off the journey. Grrr. Bloody satnavs.

if your asking this question, consider that your may have brought the wrong car

at then end of the day if you cannot afford to run it do not buy it

That's not very helpful is it?

That's not very helpful is it?

Maybe not but it is true.

Possibly the OPs circumstances have changed and depreciation means it's not economical to change. But there is very little you can do to change the mpg of a car much; unless you drive like my wife.

Possibly the OPs circumstances have changed and depreciation means it's not economical to change. But there is very little you can do to change the mpg of a car much;

It depends how you've been driving it in the first place.

As I mentioned earlier in the thread there was a difference of over 40% in fuel economy between driving my car economically and driving it fairly hard.

So there are potentially large savings to be had, although I would say that the difference between an average driving style and economical driving might only be 10-15%.

Tsk tsk. 90mph. Seriously though would doing this not get tedious after 3 hours? Plus is it even possible on congested roads? Think you would get flashed a lot.

Plus it rather ignores the 1st law of thermodynamics, so am not sure it wouldn't in fact be worse than cruising at a constant speed due to hysteresis effects.

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As many comments above, driving technique makes the biggest differance to mpg, I was told once to drive like a top chauffeur , ie as smooth as possible, anticipate & brake as little as you can, select the right gears, dont labour the car in high gears or scream it in to low a gear if a manual.

Also be wary of cheap Supermarket fuel, there are quite a few articles on the net where cheaper fuels arent actually cheaper as the mpg is less, likewise higher Octane can sometimes give better. I always buy Shell from our local garage opposite Tescos so prices are always keen

Edited 29 January, 201313 yr by Stuart_J

Plus it rather ignores the 1st law of thermodynamics, so am not sure it wouldn't in fact be worse than cruising at a constant speed due to hysteresis effects.

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Not sure ill understand the answer but - What the hell is the "Hysteresis Effect"??? For the sake of this thread lets assume i know bugger all about thermodynamics.

I think the simplest way to describe hysteresis is; a delay in getting the energy back that you put in. So if you burn fuel to get you to a certain speed you have given the car more energy, you then stop accelerating and allow it to coast. It slows down, effectively using up the energy you have given to the car. The losses can come in this scenario from the fact that some of the energy wasting factors during the input are different from the energy wasting factors on the output so theoretically all the energy you put in is not returned to you in the form you require. err I think

Having read this thread yesterday on this mornings commute I put the theory into practise. My 30 mile commute is mostly A roads in north Wales with 20 miles of the A55. I kept to the speed limit, watched my breaking and used cruise control.

My computer suggested 62 MPG!!

I think the simplest way to describe hysteresis is; a delay in getting the energy back that you put in. So if you burn fuel to get you to a certain speed you have given the car more energy, you then stop accelerating and allow it to coast. It slows down, effectively using up the energy you have given to the car. The losses can come in this scenario from the fact that some of the energy wasting factors during the input are different from the energy wasting factors on the output so theoretically all the energy you put in is not returned to you in the form you require. err I think

Close enough. In effect, the extra energy expended to accelerate to high speed is not fully recovered during the coasting phase. This will be due to several factors, not least the efficiency of the engine at different speeds and different loads. So even if there was a zero hysteresis, at best the energy to get from point a to point b would be the same whichever method you used. In the real world though, using inclines and optimising engine speed load ie driving to constant power might be more efficient than constant speed.

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Remember at school Force = mass * ACCELERATION and Work = Energy = Force * DISTANCE.

So accelerating over a distance uses energy = fuel

Also you are working against air resistance which increases as the square of the speed. So faster is MUCH worser. (yes I know)

"Pulse and Glide" is not just stressful and dangerous, it also wastes fuel. Thats why economy driving tests dont do it.

http://cars.uk.msn.c...ld-your-car-get

Phil says "Sometimes the gear you think is not always the most economical and changing down can sometimes give you better economy"

when I first got my car i drove for maximum economy, getting up the gearbox & into 5th at the first opportunity, but keeping the speed down. Result - poor economy because the engine was straining all the time. Also running cold gunged up the turbo - NOT ECONOMICAL!.

I remembered in my automatic V70 the revs stayed at 2000 when driving. So i tried driving like that - economy improved dramatically.

Edited 2 February, 201313 yr by john.errington

Got 66 to the gallon to work this morning, very nicely done it was.

Did read 68 at one point but needed to accelerate to get into work

Discovered almost by accident last week,(as if I didn't already know) that stop start driving due to the ever increasing number of ruddy traffic lights is a MASSIVE fuel user.

6 mile journey to the gym is riddled with them, but on this occassion, every single set was on green, and coupled with the 40mph limit, the Octy was showing a staggering 56 mpg by the time I got there!

Did the same journey on Friday evening, and it was the usual stop start, stop start, stop start every 300 yards or so, with the resulting and back to normal 46mpg over the same distance.

More traffic lights on red, the more revenue for the government, or am I being just a tad over cynical?

I rest my case.

More traffic lights on red, the more revenue for the government, or am I being just a tad over cynical?

Not over cynical, but you overestimate the gov's tax-collecting averice. The traffic lights are simply there to delay you and to discourage you from using your car. Hope that helps