Originally Posted by chicadam
800km is really amazing... did you do anything to your car?
I consider myself a somewhat conservative driver and I get like 625KM, mostly highway. Which is already really good...
Premium gas should not make too difference in KMs, lower octane just gives your car bad performance.
xxtrem, the 323i has a bigger engine, 2.5L, also a heavier car, so along with driving style in the City or the Highway it could be +/- 150km.
Cold air intake (biggest mileage gain for sure), Stebro exhaust (didn't see much mileage difference after that, but any gain would be negated by me stomping the gas all the time to hear that amazing sound), and UUC underdrive pulleys, which would only affect mileage with the A/C on since the A/C is underdriven now. Keep in mind that the 800KM I spoke of is on long drives ONLY, at consistent speed. I never get that good in the city (of course).
If you guys don't have a CAI yet, I'd get one. I paid $250 for mine a long time ago and its the best thing I ever did. Nothing but benefits, with the only 2 negatives being: 1) removing the filter for cleaning is more painful than stock, and 2) the CAI whistle noise (which I don't mind at all).
And NEVER use crap 89 octane. Paid the extra dime and get supreme. You drive a BMW, so don't go cheap on the blood in its veins! Your engine will thank you in a few years.