Petrol

Interesting, but not especially surprising given the car & mileage involved.

My experience was as follows:
Brand new M135i, only ran it on regular, whatever was convenient (supermarket, branded, whatever was closest at the time).
From new until around 13,000 miles the economy steadily improved all the time, presumably whilst everything loosened up from being brand new to properly run-in. I would regularly see north of 38mpg on a typical journey and saw 44mpg on a return journey at its best!
Economy was pretty steady from 13,000 mile to around 45,000 miles, and then began to steadily decline, to the point where I couldn't get more than 35mpg from it, even driven carefully.
From this point on I began using, almost exclusively, premium branded fuel, normally either BP Ultimate or Shell V-Power.
From 45,000 miles until around 55,000 miles the fuel economy began to improve until it got back to the level I used to see at the ~13,000 mile mark.
I sold the car on ~72,000 miles having averages, since day 1, 34.2mpg from it.

I couldn't tell any difference in feel or pace between regular and premium (it pulled 350hp on the OcUK dyno day on supermarket unleaded), but I assume the gradual decrease in economy was due to injectors being fouled up, and the subsequent improvement from switching to only premium fuels eventually got them nice and clean again.

In the M3 I've done ~22,000 miles so far and have ONLY filled it with V-Power, but this engine is tuned for it. It's averaging 29.2mpg under my ownership.
 
Interesting, seems good M3 figures vs M135i , is that down to particular engine technology(cylinder shutdown), lower weights, aero. ?

Not sure I would necessarily discern a 10% economy loss, since with short commute rarely brim tank (saving weight) to allow checking mpg,
and don't have a mpg readout, are they as inaccurate as speedos. ...


Tesco's momentum 99 down to 133.9 from 135.9 over previous month - so that's good
 
jpaul said:
Interesting, seems good M3 figures vs M135i , is that down to particular engine technology(cylinder shutdown), lower weights, aero. ?
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The engines in the M3 and M135 are somewhat similar but in the details quite different with the M3 producing a lot more power (420 vs 320 hp). There’s no cylinder shutdown on the M3 or M135 but there’s very little weight difference between the two and I expect that the M3 has lower drag coefficients than the M135.

The M3 also uses the M-DCT gearbox instead of the ZF8, which means you lose the coasting function and I think the final gearing is slightly different, but at the end of the day when it’s producing around 30% more power the economy difference isn’t so bad. The M3 uses about 15% more fuel than the M135 in my experience.
 
jpaul said:
Cambridgeshire ..

looks like we should all move up to Aberdeenshire (2 posts on previous page showed similar price to 1.35, so I thought I was par)
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Depends where you go. Out of town the prices reflect yours, but Tesco Danestone has been massively cheaper recently.
 
Havana_UK said:
The engines in the M3 and M135 are somewhat similar but in the details quite different with the M3 producing a lot more power (420 vs 320 hp). There’s no cylinder shutdown on the M3 or M135 but there’s very little weight difference between the two and I expect that the M3 has lower drag coefficients than the M135.

The M3 also uses the M-DCT gearbox instead of the ZF8, which means you lose the coasting function and I think the final gearing is slightly different, but at the end of the day when it’s producing around 30% more power the economy difference isn’t so bad. The M3 uses about 15% more fuel than the M135 in my experience.
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I thought that the only similarity was the capacity:D. I actually thought that DCT had coasting too.
 
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