I just picked up a used 98 740i--- white / tan Lots of upgrades--- WOW what a sweet car.. Book says 89 octane OK -- 1) does it run better with 92? 2) What is to expected on MPG? freeway at 80 relatively smooth and around town - stop and go-- thanks in advance It really is niceer than I thought it could be. I just sold a 92 735i, real nice but time for a better long distance car.