Data on MPG over time (calling all nerds)

G

groovy_hippy

Member
 Derby
So ever since I've had my first car I've always kept a 'fuel book' - don't laugh - every time I fill up I diligently write the date, the mileage, how many litres and how much it cost me. It's a bit of a family tradition passed down through generations ha!

Anyway, now we've all got a lot of free time, I thought I'd satisfy the inner nerd and do some stats from this data I have for the Z (N52, 2.5i with circa 98k on the clock).

What I've learned (aside from that I am a bit odd :P ):
Total miles covered: 39614 miles
Time owned: 7.4 years
Total fuel used (How big is an oil tanker? :? ): 6770 litres
Total cost of fuel (eek): £7972.52

Average time between fill ups: 12 days
Average fill up amount: 40.06 litres
Average fill up cost: £47.17

Average cost per mile: 20p
Average miles per gallon: 26.6mpg
Max amount in one fill up: 48.38 (yeah, might've been running on fumes that day.... :lol: )

Interestingly, the mpg has gone up over the years I've owned the car (from abut 24mpg to just over 27mpg). Maybe I'm getting less lead-footed in my old age? Or the engine is loosening up (doubt it as it'd done about 40k when I bought it), or I'm just doing different driving now?

Anyway, I thought this might be interesting/amusing/scary/reassuring to someone!
 
groovy_hippy said:
Interestingly, the mpg has gone up over the years I've owned the car (from abut 24mpg to just over 27mpg).
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That's the benefit of global warming. Average temperatures are rising, so the air is less dense, therefore less resistance, easier for the engine to push the car through it = better fuel consumption.

Well................it's a theory :D
 
Interesting!

So many variables at play so probably very difficult to put a finger on it. Perhaps you have gear selection on frequent roads down to a tee, now you've been driving it for a while.

To contrast, induction is more efficient with cold/dense and dry air. So which one of those wins i'll let you decide!
 
You'll get higher mpg if the car is aerodynamically polished as there will be less resistance when moving. Scientifically proven fact i've just made up. :rofl:
 
Remember that you'll get a seasonal variation - fuel quality changes seasonally (i.e. "winter diesel"), in the winter you use lights and heating more. If it's a second car that you use less one winter than the next it might make it seem like the economy on average is improving.

In the 7k I've done in my Z4 (that's depressingly low) I've averaged 29.7 MPG, £0.15 a mile.
But when you add in running costs (repairs, servicing, depreciation), it's more like £0.42 a mile.
 
I'm not going to write mine all out, but it can be found on my Fuelly profile.

Summary: 81,692 miles tracked (of 150,000-ish) - covers commuting, weekend drives, track days and Ring trips.

Average MPG: 26.6
Best MPG: 32.5
Worst MPG: 11.4

Fill ups: 375
Total litres: 13,954
Total £ spent: 18,527
Average £/litre: 1.33
Average £/mile: 0.22
 
IroningBoard said:
To contrast, induction is more efficient with cold/dense and dry air. So which one of those wins i'll let you decide!
Click to expand...

But cold/dense air requires more fuel added to keep the same 14.7:1 ratio. (Ideal world figures)
 
mmm-five said:
I'm not going to write mine all out, but it can be found on my Fuelly profile.

Summary: 81,692 miles tracked (of 150,000-ish) - covers commuting, weekend drives, track days and Ring trips.

Average MPG: 26.6
Best MPG: 32.5
Worst MPG: 11.4

Fill ups: 375
Total litres: 13,954
Total £ spent: 18,527
Average £/litre: 1.33
Average £/mile: 0.22
Click to expand...

"Worst MPG: 11.4"

Good effort.
 
skelters said:
"Worst MPG: 11.4"

Good effort.
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That was at the Ring, and I did 3 tanks of fuel overall. Filled up when I arrived, filled up again before the afternoon restart, and filled up again to drive home.

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Z4M is much cheaper to run in every way to an e34 M5 - which I got down to 6mpg at the old Anglesey circuit, but that never got higher than 3rd gear.
 
Had a 2007 plate A**i S3. Maximum was 29mpg. Lowest was 12mpg.

Highest I've had with the 3.0si is 41mpg with the roof down. Lowest about 24mpg.
 
Our Jaguar XK8 in sport mode and "using it" it returned 2.3mpg :o :thumbsdown: I couldn't have tipped it in from a bucket any quicker!! Best I ever had was 28mpg ( long motorway run on cruise using the torque ) the Z is positively frugal compared to that.
 
I'll have to confess to nerdery then. :oops:

I just grew up with it, my Dad kept a book and when she got a car so did my Mum so I just thought it was normal and did the same for each car or bike I owned!

But it's much easier since I gave up the book and calculator in favour of Excel. :lol:

I had my 1st E86 for 23 months and did 8,036 miles with it at an average of 32.36mpg.

I had my 2nd Coupe for 33 months and did 13,947 miles in it at an average of 34.24mpg.

Much better than my 2.8 Injection Capris managed, but then I'm a bit less of a hooligan now!

And 95% of my driving with my Coupes was 30+ mile trips on A-Roads and Motorways with no commuting.

It's too early to tell with my M, but I know it will use a fair bit more - when I can use it. :(
 
Have you put the whippy back on ? That improves aerodynamics and therefore MPG. :whip:
 
NickDE said:
Have you put the whippy back on ? That improves aerodynamics and therefore MPG.
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That must explain the difference! :lol:

My 1st one had a stubby and my 2nd a whippy, until I put a semi-whippy on it a year or so ago.
 
Mr Tidy said:
NickDE said:
Have you put the whippy back on ? That improves aerodynamics and therefore MPG.
Click to expand...

That must explain the difference! :lol:

My 1st one had a stubby and my 2nd a whippy, until I put a semi-whippy on it a year or so ago.
Click to expand...

Not sure this is the forum for admitting you have a semi-whippy? :cry:
 
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