Which grade petrol?

[Darlo74]

I've just bought my first BMW - MY08 335i Cab - and am enjoying finding out about its limits.

Question is, what's the best grade fuel to use - will I get better performance, mpg etc using a higher octane? What are people's experiences, and I'm presuming Tesco's 99RON is fine even though on the fuel filler flap it states to use between 94-98RON?

Darlo

[john_p]

You won't notice a huge difference (if any) using super unleaded over unleaded. 98/99 will be fine, but the car is designed to run on 95, and is not able to make full use (for want of a better description) of the extra "octanes".

M-engines, on the other hand, are designed to run on 98, and produce their rated power doing so. If you use 95 with them, they won't produce the full rated power and mileage goes off a bit.

[AdamD]

I'm not so sure they are designed to run on 95 RON especially if its turbocharged. Even my humble 3.0 Z4 with the old M54 engine states that it should be run on 98 RON to make the quoted power figures of 231ps (although anything down to 91 is acceptable with a loss in output).

[blank]

It's worth using Ultimate/V Power just for the cleaning properties IMO.

I've seen results of a test comparing Ultimate and "normal" 95 and it's quite staggering. See if you can find anything on the BP Audi that runs (I think) 1 bank on Ultimate and the other on regular.

[stevesingo]

http://www.bp.com/sectiongenericarticle.do?categor...

Steve

[Darlo74]

That's a striking difference, think I'll run it on 98/99 RON for a while and see what discernable differences I notice. Regardless, if BP Ultimate does what it says on the tin its seems like its best to stick with the higher octane.

[blank]

stevesingo said:

http://www.bp.com/sectiongenericarticle.do?categor...

Steve

That's the one. A mate of mine was very involved with the bike tests. The difference is pretty astonishing. For an extra couple of quid per tank I think it's generally worth it to go for the super unleaded.

[stevesingo]

I borrowed an endoscope last year to take a peek.





Had been run exclusively on V Power for the last 18k.

E30 M3 BTW.

Steve