My Fuel Economy Investigation (Petrol)

[burns863]

Well, after a few months of investigating, over many many tanks of fuel, I would like to share my findings with you all as it may even be of help to some, if not interesting to the rest of you

Not firstly, I do around 600 motorway miles per week in my 2002 Mini Cooper (Chilli), so I have had the chance to go through many tanks of petrol! I have unfortunately not got the OBC so havent been able to easily record MPG readings. I must take the time to work mine out! However, the purpose of my investigation wasnt really to find the exact MPG figures, it wa sjust to find out which fuel seems to suit my Cooper better

Now when I first started using super unleaded I went for the BP Ultimate 97 Octane. Now stepping up to this I noticed a definite improvement on economy (after a a few tanks of it). I was getting round 50 miles out of it with motorway driving. When it came to driving around town I didnt really see much improvement.

After the Tesco Fuel crisis had died down I decided to give the Tesco Super Unleaded a go. Now unfortunately I cant find a store anywhere locally, or along my route to work that sells the Super Unleaded 99, so I had to go with the 97. This being the case I didnt think it would be any different to the BP 97, however again, with motorway driving I saw a definite improvement over the BP! Granted, not by much, probably an extra 10 miles or so out of a tank but the Tesco fuel is also cheaper, so I was impressed Less money and even more miles!

Before stepping up to a 99 octane fuel I gave the Esso Super unleaded a try and found it to be just as good as the BP Ultimate.

So... next came the Grand Daddy.. I started to run with Shell V-Power. Now the first time I filled up with V-Power I used up the tank with mostly town driving but a little extra urban. I didnt really see any improvement over the cheaper 97 octane fuels, but I am wondering if I needed a couple of tanks for the ECU to adjust? So.. despite being dissapointed with the first tank I filled up again for the Lakes and Mountains Run in Wales. Now this time, I was impressed I spent most of the run in 3rd and 4th gear (Damn you S's as the front ). High revs, hard braking and generally what I would class as fuel hungry driving. This didnt make a difference though! I was able to acheive the same number of miles out of my full tank, as I was during motorway driving with the cheaper fuels Great!

BUT (yes there is always a but!...)... following my great experience with V-Power I carried on using it, despite the high price! Not since then I have only used V-Power and have again found that with Urban driving then it is incredibly efficient! The problem came during the week with my commuting journeys to and from work. The V-power - wierdly - doesnt give as good economy on the motorway, as the cheaper fuels do With this one I am confused. A few more tests with Urban driving and again the V-Power delivers, so why not when driven extra urban?

I have recently switched back to Tesco 97, Im on my second tank for my commutes to and from work and my economy has improved as I expected, over the V Power.

Just to confirm, I tried to make sure I drove in the same style during this whole investigation and keep all constraints at a constant. Obviously there will be slight differences as somedays there is more traffic than other days. However I think I have gone through enough full tanks to be able to make the judgements I have.

Conclusions
BP Ultimate 97 - Good Improvement all round over Unleaded 95

Tesco Super Unleaded 97 - Good Improvement all round over Unleaded 95, slightly more efficient than BP Ultimate 97

Esso Super Unleaded - Good Improvement all round over Unleaded 95

Shell V-Power - Incredible economy for Urban driving. Not so good for Extra Urban

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I hope this has been of interest or even help to some. I would greately appreciate feedback, questions, and personal experiences And can anyone help me out with V-Power issues?

Kind Regards

Dan

[ALD0]

Good write up on your petrol findings, I switch between V Power and also Tesco Supoer unleaded.
Both offer a points system (just earned £10 money off voucher for Shell) and Tesco send out Quaterly vouchers, this is where I get my money back with the different variences between the fuels.

Si

[Paul]

I always use Tesco 99 in the S when I can (and as Tesco is about 3 miles away, that's most of the time) and it seems very good to me.

[NeuroBeaker]

I'm a regular user of Sainsbury's Super Unleaded 97. I've been quite happy with it, but it'd be interesting to see how it would perform against the others.

As you've driven all the others already, do you fancy adding one more to the review, Dan (assuming of course you can find a Sainsbury's petrol station)?

All the best,
Andrew.

[burns863]

Quote: Originally Posted by ARCrawford (original)

I'm a regular user of Sainsbury's Super Unleaded 97. I've been quite happy with it, but it'd be interesting to see how it would perform against the others.

As you've driven all the others already, do you fancy adding one more to the review, Dan (assuming of course you can find a Sainsbury's petrol station)?

All the best,
Andrew.

If I find a Sainsbury's petrol station in reasonable reach to be able to fill up there often for a while the sure, I can give it a go But I am unsure on where the nearest Sainsbury's to me is actually. I will look into it. I think the outcome though will be similar to the tesco fuel

Any ideas anyone, on the wierd V-Power behaviour?

[humph]

Very interesting Dan. I do about 400-500 miles a week in my Oct 06 Cooper works. My commute can be broken into sections. On the way to work 15 mins of urban driving, 30 minutes of crawling on the M60, then open motorway (M62, M6) for 20 minutes, and finally 10 minutes of national speed limit A roads (hard accelerating from lights here). On the way home it is reversed but without the crawl on the ring road. I run a comprehensive excel spread sheet for my fuel consumption and cost per mile (work requirement) because the OBC is unreliable to say the least. I too have found that V power offers very little in the way of extra MPG on the motorway, but does last longer on the urban cycle. My fuel alternates between V Power and Total Excelium. Currently my car delivers the same MPG (Average 33.4) on both fuel types but the Vpower is more expensive. I do honestly believe the car pulls better on Vpower but this may be me trying to justify the extra 3p per litre.

Results from my sheet for those interested are.

Total Miles Travelled To Date 13816 Miles
Average Distance Travelled Between Fill Ups 288 Miles
Total Amount Of Fuel Used 415 Gallons
Average MPG 33.4 Miles/Gallon (MY OBC Says 35.4)
Total Cost Of Fuel Bought To Date 1742 Pounds
Average Price Per Litre 92.2 Pence
Average Cost Per Mile 12.6 Pence/Mile

[NeuroBeaker]

Thanks Dan!

As for the Shell V-Power, higher octane fuels are not strictly more explosive than lower octane fuels, it's that they have been stabilized to avoid early detonation during higher compression. I've read that many high performance engines are designed to run best at the highest octane rating they can get because they adjust the compression to suit the fuel they're using - while sticking high octane fuel in a car like a Robin Reliant will actually slow it down instead of making it faster.

When an engine runs at higher revs, presumably the pistons will compress air/fuel mixtures more quickly prior to ignition. Is it possible that the Shell V-Power is only really efficient when running at these higher compressions and you're not getting the full benefit when cruising at high speed and low revs?

All the best,
Andrew.

[humph]

Shell sell V-Power as a fuel developed with the Ferrari race team. To this end perhaps it does perform better when the engine is being driven in a 'race' style i.e. high revs, lots of gear changes, and acceleration.

[burns863]

Quote: Originally Posted by Humph (original)

Very interesting Dan. I do about 400-500 miles a week in my Oct 06 Cooper works. My commute can be broken into sections. On the way to work 15 mins of urban driving, 30 minutes of crawling on the M60, then open motorway (M62, M6) for 20 minutes, and finally 10 minutes of national speed limit A roads (hard accelerating from lights here). On the way home it is reversed but without the crawl on the ring road. I run a comprehensive excel spread sheet for my fuel consumption and cost per mile (work requirement) because the OBC is unreliable to say the least. I too have found that V power offers very little in the way of extra MPG on the motorway, but does last longer on the urban cycle. My fuel alternates between V Power and Total Excelium. Currently my car delivers the same MPG (Average 33.4) on both fuel types but the Vpower is more expensive. I do honestly believe the car pulls better on Vpower but this may be me trying to justify the extra 3p per litre.

Results from my sheet for those interested are.

Total Miles Travelled To Date 13816 Miles
Average Distance Travelled Between Fill Ups 288 Miles
Total Amount Of Fuel Used 415 Gallons
Average MPG 33.4 Miles/Gallon (MY OBC Says 35.4)
Total Cost Of Fuel Bought To Date 1742 Pounds
Average Price Per Litre 92.2 Pence
Average Cost Per Mile 12.6 Pence/Mile

I also use the M60 Your spreadsheet looks really useful by the way!

Seems as if you have definitely found the same as I have then. I think my best option would be to use V-Power at weekends as I do more urban driving, but use a lower octane fuel for my daily commute!

Do you know anything about how the ECU adjusts to suit different fuels?

Quote: Originally Posted by ARCrawford (original)

Thanks Dan!

As for the Shell V-Power, higher octane fuels are not strictly more explosive than lower octane fuels, it's that they have been stabilized to avoid early detonation during higher compression. I've read that many high performance engines are designed to run best at the highest octane rating they can get because they adjust the compression to suit the fuel they're using - while sticking high octane fuel in a car like a Robin Reliant will actually slow it down instead of making it faster.

When an engine runs at higher revs, presumably the pistons will compress air/fuel mixtures more quickly prior to ignition. Is it possible that the Shell V-Power is only really efficient when running at these higher compressions and you're not getting the full benefit when cruising at high speed and low revs?

All the best,
Andrew.

I was hoping for a detailed reply like this Chemistry Man I understand what you mean, I was under the impression of them being "more explosive" as you put it

Quote: Originally Posted by Humph (original)

Shell sell V-Power as a fuel developed with the Ferrari race team. To this end perhaps it does perform better when the engine is being driven in a 'race' style i.e. high revs, lots of gear changes, and acceleration.

Perhaps this is the case! Now I have read Andrews information on the fuel itself this explanation seems to fit the bill V-Power definitely seems the best bet for Runs then!

[Root Ginger]

Just seen this thread,

I found that when Optimax switched to V Power I lost 20 to 30 miles from a tankful of fuel overnight I do Urban driving when I'm off and motorway miles to work.

I now use Tesco 99 and that restored the drop in economy. I alternated tanks for a while before I changed and my findings were that I consistently got 20 to 30 miles more out of the Tesco fuel.

The other thing I noticed was that on V Power I would get better response to an immediate push of the throttle over the Tesco fuel but after that it seemed slower. The Tesco fuel didn't have this little extra burst but felt smoother and faster all round over the V Power.

[burns863]

Quote: Originally Posted by Root Ginger (original)

Just seen this thread,

I found that when Optimax switched to V Power I lost 20 to 30 miles from a tankful of fuel overnight I do Urban driving when I'm off and motorway miles to work.

I now use Tesco 99 and that restored the drop in economy. I alternated tanks for a while before I changed and my findings were that I consistently got 20 to 30 miles more out of the Tesco fuel.

The other thing I noticed was that on V Power I would get better response to an immediate push of the throttle over the Tesco fuel but after that it seemed slower. The Tesco fuel didn't have this little extra burst but felt smoother and faster all round over the V Power.

Thanks for sharing your findings I really need to use this Tesco 99 fuel! Need to try and find the nearest place to me that does it!

When you used V-Power did you notice that although you lost mileage on the extra urban drives, that it was actuually really good driving round town?

[StumpyPete]

Interesting thread - I normally use standard shell unleaded in the MC, but I use V-Power all the time in my X5. I found that it gives me about 2mpg more than standard fuels. Had to stick some normal BP in last week, and boy has it been sluggish, MPG back down too! On the change from optimax to V-power; i found very little difference in fuel economy but did notice the better acceleration.

[humph]

Quote: Originally Posted by burns863 (original)

Your spreadsheet looks really useful by the way!

Yes it is , shows me exactly how much all my business miles cost me on top of what the company pays per mile.

If you would like a copy PM me, that goes for anyone.

Quote: Originally Posted by Root Ginger (original)

The other thing I noticed was that on V Power I would get better response to an immediate push of the throttle

I have to agree that on Vpower mine gives more of a kick in the back when you hit the gas.

[Root Ginger]

Quote: Originally Posted by burns863 (original)

Thanks for sharing your findings I really need to use this Tesco 99 fuel! Need to try and find the nearest place to me that does it!

When you used V-Power did you notice that although you lost mileage on the extra urban drives, that it was actuually really good driving round town?

I lost mileage consistantly across all driving, although I've always got more driving around town, than the short motorway jouneys I do anyway. This was even on Optimax, around 10 miles a tank more.

My car was tuned to run on Optimax so maybe this is having an effect here too. Standard S's, Cooper's or One's may behave totally differently.

I notice you say you have a Cooper Works like I used to own Humph. What version do you have?

[humph]

Quote: Originally Posted by Root Ginger (original)

I notice you say you have a Cooper Works like I used to own Humph. What version do you have?

I say Works, but it is the Sound kit. The true works like you had was long gone before I bought either of my Coopers . Do like the sound kit very much though. Just need a manifold and she'll be just as I want her.