We have the same car also - when we first got it ran it on 91, was using a ton of gas (350k to tankish) and had jerky horrible performance - dealer changed the 02 sensors and AFM, and recommended 98 - would never look back, after an ecu reset we are getting about 500kms of city driving and about 650ish on open road....i don't think it's too bad, my bc5 gets about 350k to a tank on a good day lolz