Your MPG seems a little bit low. I monitored mine for 3 years and averaged 19MPG on long, highway journeys and 14MPG on my daily commute (I-395 into DC). Ref octane rating I used all grades of fuel and didn't get any noticeable changes in MPG, performance or knock. Handbook recommends premium gas, so I used that nearly all the time.

By the way, I'm in UK now and gas prices here are about $6.20 per gallon!! What we all need is an Raider/Montero/Pajero electric motor conversion <img src="/forums/images/graemlins/ignore.gif" alt="" />