Gas Mileage Thread (come here for answers)

[oranger]

here's a couple of interesting reads:

http://www.geocities.com/motorcity/l...0/octane1.html

You should use the minimum pump octane (AKI) fuel that will run in your engine without knocking. You're wasting your money on higher octane fuels if there aren't needed to control knock. The two most common myths regarding pump octane (AKI) are that it will increase performance and result in better fuel mileage. You may see improvements in your ride due to the cleaners in higher grade, higher quality fuels, but octane by itself will not have any effect.

http://theserviceadvisor.com/octane.htm

You can, but there are no real benefits, other than the gasoline manufacturers making more money off of you. When you use a fuel with a higher octane rating than your vehicle requires, you can send this unburned fuel into the emissions system. It can also collect in the catalytic converter. When you over stress any system, it can malfunction or not do what it was designed to do properly. In the early 90's, an early warning symptom was a rotten egg smell from the tailpipe. Easy fix, go back to using regular 87 octane gasoline. The rude odor usually disappears after several tanks of gasoline.

each excerpt is sited from the corresponding article link. there is a littel more reading in each one if you're interested

edit: another one:
http://www.ftc.gov/bcp/conline/pubs/autos/octane.shtm

Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.

for those of us with stockish f22s and a low compression ratio, the 87 should be fine if not a little better than a higher octane gas

Interesting, but practical experimentation is on my side. I have a 6mpg difference between regular and premium. How do you explain that, if not by the gasoline. And that is over 5 tanks each, not just one tank.