What mods have improved your mpg?

[InuFaye]

weight reduction.

[e30jake]

The diff and driver make a big difference. A taller diff can help your mileage decently. If it's your early 318i, a mid-low 3.XX diff could improve your mileage.

I'm more interested in this for my IX right now actually since I'll be leaving for school in a month and probably taking it with me. As far as my 318i though, the diff is the least of that things problems right now

I have heard people say they got better mpg with an m30 afm or miller maf and bigger injectors... anyone have before and after numbers or estimates on this?

[gearheadE30]

diff and turbo, believe it or not. Though the turbo also involved a wideband, which I think allows my tune to be a bit leaner at cruise than stock.

[Vivek]

The diff and driver make a big difference. A taller diff can help your mileage decently. If it's your early 318i, a mid-low 3.XX diff could improve your mileage.

[brian52555]

6 Speed

[tonerrrr]

You have the most effect on your gas mileage.

02 sensor since you can just buy one for <$40 / splice the wires and it has probably never been replaced on your car.

[ZinnoBerrotEta]

O2 Sensor, big time. Cat, good exhaust. Refurb'd AFM/MAF http://www.r3vlimited.com/board/show...83#post3152483

[VinniE30]

the lead foot mod doesn't help

[e30jake]

Maybe this thread will be a complete failure, but whatever. I, like many r3v members, am a broke college student who blows money on my cars instead of things that could probably be more useful. I'm fine with that. Anything that will help pay for itself in the long run though is definitely helpful though, or even anything that left your mpg unchanged. Have at it.