So - What fuel works best in my car? Do I go for cheap-o Tesco fuel, or Tesco Ultimate - how about Shell or BP? I can't find a definitive answer, so theres only one way to find out - The MPG challenge.

Heres what i'm doing:
Filling my car up with fuel "X" from a virtually empty tank,
Reset the trip counter,
Drive 'till the tank is under a quarter full (my fuel gauge is wrong so it's virtually empty at this point),
Fill 'er up till she's full with fuel "Y",
Take the amount of fuel that i've put in (which is the amount i've used) and bung it in this spreadsheet I made.

Currently done Tesco & Tesco Ultimate, will post the results up in a screenshot 'till tonight.

I will be using my "normal" driving style (relaxed with the occasional crazy bit). The car has a full tank of Castrol GTX oil and have given it a shot of Redexx so everything should be "controlled".

OT - How much "extra" can you fit in the tank over when it clicks? Usually when it clicks I fill it up to the nearest Litre or £ depending on the petrol station to give me more reward points (as i'll use the extra fuel anyway).

The spreadsheet i've done only does Litres / Miles / MPG atm but feel free to fiddle around with it.

Just go for the cheap fuel. In a car with an engine under 2,0L (I presume that's what you've got) you won't see any great improvement if you use Ultimate instead of normal, it should be just 1-2% so it isn't worth it.

*facepalm*

Can you back that up with any evidence? Didn't think so - thus the reason why i'm doing this...

You won't notice any difference in power (although Bambo is wrong to suggest engine capacity has much to do with that), but you will, I predict, notice a decent mileage increase on good fuel.

May I suggest a tweak to the test though. Make in longer term, with say 3 months on each fuel and the average mileage, cost per mile and miles per tank figures noted. Doing the test on a single tankful of each fuel isn't going to give meaningful results.

Try this website instead of your spreadsheet. I haven't started using it for my car yet but I worked it out around 10p/mile

if you really want to see a clear back to back difference between fuels, use at least 2 full tanks of fuel before switching. When only using one tank of, say fuel X and going to fuel Y the next fillup, there's still fuel X in the tank, lines, filter and so on. This might affect results..

edit: meh, tristan beat me to it basically...

Quote from tristancliffe :

(although Bambo is wrong to suggest engine capacity has much to do with that)

Weird, I remember seeing a video in which an engine such as a 1,6L you will struggle to get 1-2hp while with a 4L you can get up to 5-10hp.

And what were the outputs, specific and total, of the engines?

Quote from tristancliffe :

You won't notice any difference in power (although Bambo is wrong to suggest engine capacity has much to do with that), but you will, I predict, notice a decent mileage increase on good fuel.

May I suggest a tweak to the test though. Make in longer term, with say 3 months on each fuel and the average mileage, cost per mile and miles per tank figures noted. Doing the test on a single tankful of each fuel isn't going to give meaningful results.

3 months would be good, but when I go to Uni I won't really have time - as it is I have 8 fuels to test, and get through a tank a week - so it's gonna be a 2 months test - if I took 3 months per fuel it'd take 2 years

So far with the three runs i've done, I've gotten 36.1 and 36.2 MPG fro Tesco Ultimate, and 35.4 MPG from Tesco Ordinary - however this was during the snow and ice and my car has been idling a lot waiting for the car to warm up / de-ice so it's probably an under-reading. Based on this it's 11.03p per mile on Ordinary and 11.57 per mile on Tesco Ultimate.

I was using a website for the reading but it's easier to use a spreadsheet - it does the same calculations but it does them all on the same page

Quote from Jakg :

So far with the three runs i've done, I've gotten 36.1 and 36.2 MPG fro Tesco Ultimate, and 35.4 MPG from Tesco Ordinary - however this was during the snow and ice and my car has been idling a lot waiting for the car to warm up / de-ice so it's probably an under-reading. Based on this it's 11.03p per mile on Ordinary and 11.57 per mile on Tesco Ultimate.

Wait until the snow/ice has gone, then you'll have more accurate readings, weather conditions have more to do with fuel consumption than the fuels themselves I think. For instance I use half a tank (ish) a week in my Focus, this week i've used just under 1/3 a tank - driving same distance.

Except I was driving on the Ultimate petrol back when it was "normal" and using the cheaper stuff when it was Icy - so Tesco Ordinary is the clear winnner.

Theres an issues of EVO from I guess a year or two back now that has a fairly comprehensive fuel test in it. Try getting hold of a copy if you can, I found it pretty interesting. I would try and scan it in for you but it wont be for a week or so as I don't have it with me atm.

Quote from Jakg :

Except I was driving on the Ultimate petrol back when it was "normal" and using the cheaper stuff when it was Icy - so Tesco Ordinary is the clear winnner.

Still doesn't make it a fair test as road conditions are completely different.

Thanks for the spreadsheet, Jack! Much appreciated

I was meaning to make a spreadsheet to work this stuff out. I do about 500 miles a week and was using a calculator to work out mileage.

I've noticed quite different figures betweeen fuels. Using Esso Diesel @ 97.9p / litre(in my little Fiat Panda Diesel) I got an average of 62.2 MPG or a cost per mile of 7.1p. Now using Texaco Diesel (again at 97.9p / litre) I've averaged 54.3 MPG!! And I wasn't driving very differently either although of course the recent weather must have played its part.

I'll keep on trying the different brands and report back sometime to give the Diesel take on things.

Thanks again!

Quote from Jakg :

I will be using my "normal" driving style (relaxed with the occasional crazy bit). The car has a full tank of Castrol GTX oil and have given it a shot of Redexx so everything should be "controlled".

It is an old unstressed standard road engine, you do not need to start adding additives to the fuel, which may have some justification for lead replacement or in specialist applications, however you do not have a fragile racing engine, nor are you running high compression.If you're worried about money don't spend it on magic all-in-one additives. Equally you do not need premium quality oils in your car, if you've got the money to spend and are going to be driving the car hard then they might be worth it, but you will be driving it round like a granny trying to save money. Whatever you do don't put in lower viscosity oils into your engine, you'll only cause damage and waste money. Just put Halfords 10W/40 in and make sure you change oil regularly, check your Haynes manual but you probably don't need to put synthetic oil into that thing.

Quote from Joe_Keaveney :

I've noticed quite different figures betweeen fuels. Using Esso Diesel @ 97.9p / litre(in my little Fiat Panda Diesel) I got an average of 62.2 MPG or a cost per mile of 7.1p. Now using Texaco Diesel (again at 97.9p / litre) I've averaged 54.3 MPG!! And I wasn't driving very differently either although of course the recent weather must have played its part.

Standard diesel will come from anywhere where its been bought on the market, one company won't supply the same fuel everytime.

it's surprising how different cars get diffeent results too

of the two diesels in our household, one prefers esso and the other prefers the "cheap" stuff from down the road though the cheap stuff is actually 1p a litre dearer than esso !, however it gets about 5 % better milage from it so i can live with a 1% aprox dearer price

I did a similar test a couple of years ago, and I found results varied by quite a large amount with the "same" fuel.

So one fill up on Tesco fuel would return less or more than a fill up on the same fuel from the same garage.

The reasons for this, I think, is that no matter how carefully you try to drive the same, its just possible to drive the same all the time.

You've got so many varibles, traffic lights, other traffic, ambient temperature while filling up, and whilst driving, humidity, load produced from electrics, variances in tyre pressures etc etc

The fuels themselves vary too - e.g. winter fuel and summer fuel; different to each other in several ways.

So ultimately the only way to do the test without compromising it would be to hire a dyno for a day and just do two stints with a gallon of each?

If I was able to boot my computer at home, I'd give ya data on differnet grades of fuel (US grades of course). I have plenty of data as I use to log fuel milage and repairs all the time.

I could use cheap fuel and drop the extra money I would have spent on the more expensive fuel in the garbage or just buy the expensive fuel and the results would have been the same.

Quote from BAMBO :

So ultimately the only way to do the test without compromising it would be to hire a dyno for a day and just do two stints with a gallon of each?

The only way to get decent results is do it under lab conditions.

Quote from BAMBO :

So ultimately the only way to do the test without compromising it would be to hire a dyno for a day and just do two stints with a gallon of each?

if you can flush the tank and fuel lines before trying the other fuel, yes

Well, if you were going to that extreme I'd use two identical engines built to careful standards, and then do 100,000 simulated miles on each using control fuels of each basic type...

But in the real world it's real world figures that matter, but I don't think a single tank is enough for the crap fuel to 'crap your engine up', or for the good fuel to 'clean your engine up'.

Quote from pb32000 :

Theres an issues of EVO from I guess a year or two back now that has a fairly comprehensive fuel test in it. Try getting hold of a copy if you can, I found it pretty interesting. I would try and scan it in for you but it wont be for a week or so as I don't have it with me atm.

Yeah I remember this, IIRC they used a Golf GTI or something, mainly to measure extra power.

Jack, how many threads till you realise you have a silly car that won't do meaningful amounts more mileage on a tank? I've tried this with my old RS, using Super Unleaded I'd get about 95 miles before the light came on, with normal it'd be around 90. 5 miles wow! Surely that's worth the extra £4 it cost to fill up when I had it

Tried it on my Z which is a more comparable subject, since I don't have to thrash it everywhere, I'd get about 150 miles normal riding (i.e 4 days commuting and a couple of days long riding) on the Normal stuff. Using the more expensive high-octane crap I'd get maybe 160 miles over the same conditions.

Honestly, if you're whinging about the fuel costs, how it's hard to afford etc, just stick with the cheap and cheerful fuel.. :doh: