After reading all of the responses on this thread I must have the best 1989, 12/88 manufacture date, E34, M20, 525i auto ever built! I get 22+ mpg city and 27.5mpg hwy and that is with spirited driving, (very seldom under 75mph). Sure the E34 is a heavy car, damn near 2 tons of high-quality German steel, and only 168hp, but I think that your problem may be with an automatic transmission that shifts between 4500 & 5000 rpm, as mine does. The tranny is set to shift at, or near to the torque peak of the engine for maximum fuel efficiency and smoothness. I found out early on that to gain maximum performance out of the M20, E34, you need to manually shift the trans. I shift mine at 6200 rpm and the performance difference is astounding! If you want to pass anyone at 60~65 mph, you have to manually downshift. I hold 3rd gear to about 5000~5500 rpm and that's good for about 100 mph! My car has the 4.27:1 differential and in D, or overdrive, 3000rpm is about 80 mph. Bottom line, the M20 engine starts to "come on the cam" as you pass about 3800 rpm, up to 5800~6200 rpm. And by the way guy's, I have 316,000+ miles on my M20, E34 and it's ALL ORIGINAL! I have the Energizer Bunny, it keeps going and going and going..........Originally Posted by SC David
21mpg on my last tank here. 80% city, 20% highway. Not too bad forcity driving.
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