What mods have improved your mpg?

[CabbE30]

I noticed an improvement of 3-5mpg when going to a lower geared diff. I also saw about 1-2 mpg with my MarkD chip/17lb injectors.

[e30jake]

You want to spend $$$ so you can get a few MPGs more. How long will you need to drive to make the initial investment back and then start saving money?

I made this thread with both performance and mpg in mind. What you say is true for many people who just want to get the absolute best mpg possible. In most cases, you're better off sticking with what you have instead of spending to try to save. I was talking more about performance stuff that would help or wouldn't hurt. I will probably end up spending money trying to improve performance no matter what, but since it is my daily driver, anything that will improve mpg will move up in the list of priorities.

[e30jake]

I noticed an improvement of 3-5mpg when going to a lower geared diff. I also saw about 1-2 mpg with my MarkD chip/17lb injectors.

What engine is this?

[Simon S]

maintenance upkeep mod

[R3Z3N]

Engine Delete Mod ftw. Rolling like the Flintstones!

[evandael]

don't pay any money for modifications to improve gas mileage. it won't make a huge difference. drive smarter, slower, and more gradually.

the best things you can do is make sure the maintenance is up to date, specifically things like...

any and all fluids
valve adjustment
uel filters and pumps
injector rebuild
new O2 sensor (hell, any and all sensors)

and making sure that..

the AFM is calibrated correctly
the brake calipers aren't seized
the wheel bearings aren't on their last leg
and tire pressure is proper


i still wouldn't expect more than 26 highway with a 325is, 30 with an eta, or 35 with a 318i. just drive it to have fun and be E30 stylin', with the decent gas mileage as a minor perk.

[TheTacoMan]

I have been getting around 32-36mpg in my 88 seta, automatic plus 2.93 diff makes first go almost 60mph. At 60mph im at about 1400-1600 rpms.

[kway]

My commute is 90 miles round trip, Nashua, NH to Boston, MA everyday ('88 325i, stock 3.73 diff). Keeping the r3v's below 3k, on bottlecaps w/cheapo 185/70-14s, I've managed an average MPG of 29 combined city/highway. I definitely lost some when I bolted on the 16s a month or so ago, and I haven't been sticking to my 3k RPM ceiling as much, more like 3500-4k. OBC is telling me I'm still averaging 24.5 MPG which isn't too bad.

For when gas prices go back up I've thought about super fuel miser mode: 175/75-14s and a taller diff, although I think the dark side will win out and it's eventually going to wind up slammed on 15x8s and retired from commuter duty.

[long tall eta]

swapped out my s54 to a b27

[Massimo]

Weight reduction don't need it remove it. Gut the trunk, interior, remove A/C, power steering delete, elcetric fan conversion.

Less right foot, more 5th gear.

[bowtie2bimmer]

Carbon Fiber metatarsus mod... work great for reducing sprung weight on the accelerometer

[Xat1cZ]

the roof , pillars and windows delete mod.

[325ix]

the roof , pillars and windows delete mod.

Nah, then you have more drag from the open top.

[JasonC]

the lead foot mod doesn't help

This is me :(. But it's hard not to lean into it all the time. Seeing i do drive a 383 stroker daily... But i do get 16mpg with city driving and a little highway tossed in there!

[bernzpeed]

i think the best and inexpensive mod I did was putting in a performance chip.
I would get about 29.7mpg @ average of 65 mph.