MPG

[Si_GTi]

Hi gang,

I'm 98% sure that this has been addressed somewhere else on the forum, but I was wondering what the conversion is for MPG and what figures I need? I've just filled up at BP, so here's what I have from the just-finished tankful of Ultimate:

Miles clocked up: 277.4
Litres of fuel that went in (the last time I went ot the garage): 34l (approx - can't remember the last few digits)
Cost: £32 approx (91.2 per litre)

The exact figures are at home on my fuel receipts, I'll get hold of them tomorrow perhaps...

So can anyone tell me, how do I get my MPG? Any help would be appreciated.

Cheers

[Tahrey1043]

First you measure your miles fill-up to fill-up (the only reliable way of knowing you've used a particular amount, and even that can vary pump to pump)

then you divide the litres by 4.54 to give gallons

divide the miles by the gallons......

i think you can guess the rest

[Si_GTi]

Thanks Tahrey,

So based on the figures in my opening post I'm managing 37mpg over a tank of fuel. I'm happy with that considering its a GTi.

Thanks again chap.

[bstardchild]

First you measure your miles fill-up to fill-up (the only reliable way of knowing you've used a particular amount, and even that can vary pump to pump)

Good point well made

then you divide the litres by 4.54 to give gallons

divide the miles by the gallons......

i think you can guess the rest

Or you can divide the miles by the litres and multiply by 4.54 to get mpg

[metz]

i got 44.4....hmm that doesnt seem too great for a 1ltr does it?

It was motorway miles for about 200 of them though, but still 44mpg aint that a little s**t?

[bstardchild]

i got 44.4....hmm that doesnt seem too great for a 1ltr does it?

It was motorway miles for about 200 of them though, but still 44mpg aint that a little ****?

Depends on your cruising altitude (speed) 1/2 to 2/3 of max rpm is comfortable cruise speed = good economy

ie 1.4 CL MKIV 5500 rpm max
half = 2750
2/3 = 3600

I tend to cruise at 3200 and get good gas mileage that way Just under 50 mpg

[Gareth_GT_Hatch]

Ive managed jsut short of 50mpg from my light blue GT, Dark blue GT has never done more than 35mpg even though I did a single journey of a full tank (london-manchester and back) In my light blue GT Id have only used one tank but in my dark blue one I used 1 and a half.

No idea what mpg the 1.4 does yet. Watch this space.

[Tahrey1043]

Damn metz you're getting greedy - that 5th gear is good but it cant work miracles

But then again it DOES depend on how fast you go --- check the archives of my arguments with Gareth My own rough results:
With the throttle buried into the bulkhead, the 1-litre bottoms out at roughly 30mpg for 90-ish, or attempting to reach it. I think it deserves a gold star for that, as in 4th it can approach the redline down hills, and can be considered "struggling" if it dips under 4500rpm...! (now you see why i wanted an 8P?)
Slowing down, high 30s to 40 is about possible at 80.
70mph-ish or a bit over translates into middling 40s (which correlates with the official figures, no less), which I'm happy about for a 14 year old SPi on a 4-speed box.
55-60 brings it comfortably into the 50s...
And, if you can stand to drive like a grandad and do 40-45, you can see 70mpg or maybe a little better. (Result of that not verified - I can't spare the time to do that kind of protracted test, as it takes forever to even burn up the 2 litre minimum fill - ie best part of an hour - and it gets so that random difference on where the pump clicks off affects the figures! plus anyone following you gets right worked up, especially if you try it, as i did with hazards blazing, down the m6..!).

Don't know if going any slower can garner a few mpg more, but by that point you're falling off the torque peak and the engine is probably getting progressively less efficient - plus the effects of wind resistance start to hold less weight below 40. (I took to trotting around at about 35-40 when i was having a poor patch, seemed to help the bills!)


For working out the mileage, i think bstardchild's method of maths is probably easier
To record the details, either a section marked out in your diary or palmpilot if you carry one of either, or making notes in your phone at the scene helps. Personally I just make sure to always get the receipt showing litres and date when I pay, and use a pen always kept in the door pocket to note down the mileage at that point on the actual receipt itself (for trips under 50 miles where ive topped up both ends, the tripcounter reading too).

Get home, retrieve receipt (or receipts if a few have built up), bung the details into an Excel spreadsheet and get the result out the other end without too much hassle

Keeping an accurate factual record like that rather than just half remembering really helps, and not only for making mileage expense claims from work!
Beating myself up a little at the mo because I forgot to mark on what the mileage was when I left my dads sunday evening, and i probably forgot to note it on the tesco's card-machine one too in all the confusion - it's gonna be quite tricky working autoroute to get the second-best mileage estimate, considering i ended up on quite a twisty ramble with the police station and all.

PS max rpm on a 1-litre: 6500rpm
1/2 = 3250 (about 55mph for me, 65 for metz)
2/3 = 4333 (about 75mph / 85mph) - covering a reasonable base of speeds, though it'll STILL sound like its being overworked at anything over 3500

Tahrey on the motorway = ~5000rpm
hehe
(I balance it out with Tahrey in traffic = engine off / idling in 4th / getting up to about 1750 before changing up, hardly touching the throttle. and still the consumption sucks. what ho.. time to get a lupo 1.0 diesel what with them being most efficient at maximum load and all)

[bstardchild]

For working out the mileage, i think bstardchild's method of maths is probably easier

Thats why I work it that way

[carmadaaron]

tahrey, u do like lengthy posts! that took me ages to read

[CalvinGTI]

haha i tend to abuse my cars, always tittering around the red band on the ole revvo, mind you isnt that what there for ?

And isnt that why ive been banned ?

DOH !

ill shut up now

Calâ„¢

[carmadaaron]

what kinda MPG do u get Cal?

[carmadaaron]

as long as the engine is warm, u can rev it till ur content and wont cause any damage. (apart from killing the MPG! )

[CalvinGTI]

i wouldnt like to know actually, i reckon to a full tank i prob get about 200 miles, or something around that

Remember though ive got 17" on there so that lowers the economy a bit too.

All i know is, im ALWAYS putting fuel in the b***h !

hah

Calâ„¢

[Tahrey1043]

Well I don't think running it constantly in the red band or on the limiter would be too good an idea, but I would like to know if there's any real extra wear & tear affected per mile for running at 5000rpm vs 3000rpm, in the same gear. It uses more petrol that way, so perhaps there's a greater shockwave force etc..........? not to mention the effects of cams vs springs on valves.