22 mpg? Why?

[automatic]

It is unlikely, but is there any chance that speedo and odometer operate independently on these cars?  

One time, the odometer on my beater '85 318 quit working momentarily for about 15~20 miles.  The speedo functioned properly all the while.

On my '91, I currently run 225/50R15s.  Their loaded radii are within fraction of inches to that of stock tires.  Speedo is still off (as if the tires are small), but odometer is pretty accurate according to GPS.

My car averages about 25mpg, 60/40 city/highway.

It is fairly common to see a broken odometer and a working speedometer so that would make me think they do work independently.

[tmorinbmw]

I've taken plenty of e30's apart and know for a fact that the odometer and speedometer don't work individualy, not supposed to anyway. If there are decrepencies between the two then check the white plastic gears that drive the two. Over time they grow brittle and loose teeth resulting in miss-readings and not functioning all together.

They're replacable, check Bavauto or someplace like that.

[tim_s]

tim s I think one thing needs to be clearafied. A US gallon is smaller than the UK or imperial gallon. So you would naturaly get a better milage calculation.

oh yeah, oops! I'll shut up then