Supermarket or Super Pricey Fuel, does it make a difference on MPG?

Robthebank

Member
HI Guys, I have been able to do the same long distance "commutes" for the last couple of weeks and will continue on a near weekly basis until Christmas.
This comprises of a 385-425 depending on hotel, journey between Cornwall and the North East of England, to give me something to think about on the journey I have been experimenting with different fuels to see if they make a difference on MPG. Once I get some good benchmarks I may move onto different cruising speeds.
These are all in a TDI75 with a re-map running A1 alloys (215/45/16).
I may convert this into a spreadsheet or do some stats in minitab if i get really bored in the hotels.
*Edit*
Note FSI users this is not for you, keep yours running on the good stuff only, your cars need the extra RON and are very fussy on fuel.
This is more about TDI's that would run on Aldi cooking oil if you wanted.

Trip 1 Cornwall - NE, BP Ultimate 75.5mpg Average | 58mph Average (65mph cruising) | 7am Start, traffic clear 15-22degc No A/C, little rain.
Trip 2 NE - Cornwall, Sainsburys 70.6mpg Average | 48mph Average (65mph cruising) | 11am Start, heavy traffic, 15-22degc No A/C, heavy rain.
Trip 3 Cornwall - NE, Tesco 75.0mpg Average | 58mph Average (65mph cruising) | 7am Start, traffic clear 15-22degc No A/C, little rain.
Trip 4 NE - Cornwall, Esso Premium 73.7mpg, Average | 48mph Average (65mph cruising) | 11am Start, heavy traffic, 15-25degc 2hrs A/C nice weather.
 
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DJ 190

A2OC Donor
These sort of figures always amaze me! I have a mapped diesel with a 6-speed box. I'm not an aggressive driver and I even "free-wheel" fairly often. My long-term average m.p.g. is 55 (that's over several 1000's of miles and is electronically determined). I thing that the best I've ever got from a trip (with 50 mph zones on a motorway) is 65 mpg. I just can't get my head around those figures that you're quoting!

David
 

Robthebank

Member
These sort of figures always amaze me! I have a mapped diesel with a 6-speed box. I'm not an aggressive driver and I even "free-wheel" fairly often. My long-term average m.p.g. is 55 (that's over several 1000's of miles and is electronically determined). I thing that the best I've ever got from a trip (with 50 mph zones on a motorway) is 65 mpg. I just can't get my head around those figures that you're quoting!

David
I will check the next tank between trip and fuel receipt to confirm the DIS accuracy, looking at Fuelly I seem in the normal range. Note this is journey specific data and a long one at that so it helps a lot, I don’t hit above 70mpg until Exeter when leaving Cornwall, that shows how much a cold start, slow narrow lanes and lots of hills impacts the mpg.
 
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damadgeruk

Admin Team
These sort of figures always amaze me! I have a mapped diesel with a 6-speed box. I'm not an aggressive driver and I even "free-wheel" fairly often. My long-term average m.p.g. is 55 (that's over several 1000's of miles and is electronically determined). I thing that the best I've ever got from a trip (with 50 mph zones on a motorway) is 65 mpg. I just can't get my head around those figures that you're quoting!

David
When you say free wheeling do you mean with the clutch disengaged or in neutral?
 
These sort of figures always amaze me! I have a mapped diesel with a 6-speed box. I'm not an aggressive driver and I even "free-wheel" fairly often. My long-term average m.p.g. is 55 (that's over several 1000's of miles and is electronically determined). I thing that the best I've ever got from a trip (with 50 mph zones on a motorway) is 65 mpg. I just can't get my head around those figures that you're quoting!

David
Hi David, I've a feeling that yours is based on a 90bhp car. Driving both a (2x actually) 90s and a remapped 75 over a few thousand miles, I can confirm that the above figures are achievable on the 75 on a long journey. If you are doing 30 or 40 miles a journey you won't get anywhere near that.

The 90s however, rarely get over 60mpg, in fact the best I've ever seen over a tankful is 51.9mpg on Project 90.

When you mention your 6-speed gearbox I am assuming you have the ratios similar to the original 90 5-speed box, just more spread out.

I know the 90s are supposed to be similar mpg on paper, but I've yet to see any evidence to prove they are in practical terms.
 

Proghound

Admin Team
I'd love to get north of 70MPG in my remapped TDI75's! Best I've had was 68MPG measured brim-to-brim when touring around Scotland this year with 3 people and luggage. If anything, I find that motorways peg the average back a bit, the runs from down south up to Fort William, and back home from Inverness, were each done on a single tank and were both mid 60's MPG, and that's with mostly sitting on the cruise control at 60mph while on motorways or dual carriageways. Where you really get the mileage is at 45-55mph - the only thing to like about those interminable stretches of 50mph roadworks :)

Edit - just to note, I use normal Shell as standard, although I'll take supermarket fuel if there's no Shell in town. The 68MPG tankfull was actually on Morrisons.
 
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Edwrai

Member
Hi David, I've a feeling that yours is based on a 90bhp car. Driving both a (2x actually) 90s and a remapped 75 over a few thousand miles, I can confirm that the above figures are achievable on the 75 on a long journey. If you are doing 30 or 40 miles a journey you won't get anywhere near that.

The 90s however, rarely get over 60mpg, in fact the best I've ever seen over a tankful is 51.9mpg on Project 90.

When you mention your 6-speed gearbox I am assuming you have the ratios similar to the original 90 5-speed box, just more spread out.

I know the 90s are supposed to be similar mpg on paper, but I've yet to see any evidence to prove they are in practical terms.
My 90 has averaged 65 mpg over the last 20,000 miles, measured at the pump, it’s best on a tank was 78.6mpg

My 75 does 55-60 over the last 2000 miles.

I drive them both the same


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PlasticMac

Member
The main difference between Super Market fuel (petrol and diesel) and Major Oil (Shell. BP etc) is the additives, most of which are aimed at keeping the engine internals clean (ie: detergents). The advantage (my opinion) of using "expensive" (Shell Nitro in my FSI) is long term reliability. The short term advantage, in terms of MPG, is, even in my opinion, marginal, and is not a justification for the extra 10p per litre. Since the FSI is designed for 98/99 octane, it's got to be Super for me, and that means Tesco Momentum, Total Excellium, Shell Nitro etc. If I want the wizzy detergents, then Tesco is out. If I'm paying premium, then I want 99 octane, so I go well with Shell.
Also, on a petrol A2, only 98/99 will deliver the performance the car was designed to give.

So, whilst MPG is interesting, long term engine wear and tear is the real test. Only time (and in my case, the EML led) will tell.
If you look at running costs, fuel is not the most significant over the long run. With our more mature "classics" servicing and repairs are likely to be the most significant over the years.
But, above all, enjoy the bl**dy thing while you can! Mac.
 

terrywindy1

A2OC Donor
This is my best in my remapped tdi 90 with a 6 speed box with shell nitro diesel
206.6 miles from North Bristol to Lancaster (Toms) did not go over 62mph
Screenshot_20190911-135317_OneDrive.jpg
 

steve_c

A2OC Donor
I like to see people who claim high mpg figures back their claims up via Fuelly, and share the data.
 

DJ 190

A2OC Donor
Just to make a few things clear ..... When I "free-wheel" I'm in neutral. It is quite surprising how long you can keep pace with other cars (that are in-gear) and even start to gain on them! Just try it!. I've got a 75, not a 90. It's been tuned to 108 BHP. I CAN see ~65-66 MPG on a fairly long run, but 75 MPG? NEVER! As I've said, I just don't drive hard and my typical cruising speed is around 70 MPH. Finally, regarding the brand of petrol. I was part of the development team that created "Shell Optimax" All fuels purchased have to be "in-spec" The raw fuel will be from the same refinery, regardless of the brand of filling station or Supermarket. What makes it different is the additive package which is added by the tanker driver who is loading the fuel prior to making deliveries. The "Shell" additive package will be "cutting edge" and superior to any other brand. Whilst still adequate, Supermarkets and other brands will be earlier and inferior. However, the fuel will still "do its job". Now if your aim is to achieve higher mileage, then you'll get that by purchasing a fuel with a higher octane rating, but that will be at higher cost. As long as your A2 is kept fully serviced and with regular oil changes, there is virtually no advantage to be gained whatever fuel you're using. (I.M.H.O.) I doubt that you'll see any difference in M.P.G. There really isn't a way to accurately check this between fuels? Even if you made the same journey with the same vehicle, you just couldn't drive exactly the same way over the whole route?
Oh well, I'm not obsessed with getting the best MPG and I always want my driving to be pleasurable. Each to their own, then!

David
 

terrywindy1

A2OC Donor
From Shell petrol station at Cribbs causeway Bristol, so from hot 23 miles to Burnham on sea
In tdi 90 notice rpm at 60 mph
Dunlop blue response tyres at 36 psi
Screenshot_20190911-145144_OneDrive.jpg
 
Start using Fuelly and we'll see what you're really getting. One-way journeys are notoriously misleading depending on wind strength and direction.
lol - this reminds me of when I first bought Baby Boomer, I was pretty impressed with the DIS showing me 95mpg average when I collected it from Bournemouth.... It continued in this vein for a couple of months until Timmus discovered the "remap" module in the engine bay (pretty much a resistor which "over-fuelled" the engine management) - disconnecting this brought the display back to what it "should" have been, about 60-70mpg.
 
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