I have a 1991 535i that typically pulls 23-24 on the highway. Since I'm running an EAT chip, I've got to put premium in it, which was $2.75 the other day here in western Kentucky. Just was wondering if anyone here had actually swapped in a taller diff ratio in their E34 for the purpose of getting better mileage. If so, which model do you have, what ratios did you swap, and what were your results?

Grace and peace,

Robert K
1991 535i