I got some "super" gas at tesoro last week so see what it would do, I drive it to and from work, and I know it gives cars better gas mielage, so I figgerd I'd give it a whack. I was searching on the internet, and it said it could actually produce less power than with regular 87 octain. My brother is a mechanic and learning to fly from the guys in our church, and I always hear them say "that oughta give it a little kick" when they stick Avgas in something.
It seemed to have more power and it averaged 34 MPG. I have a little hotter spark plug in it. but other than that its stock.
Its a 2005 honda rancher 450 (carbourated). it has almost 9000 miles on it. so, would it run better with "super" 90 octain gas, I know cars run better, expecialy old cars. if it has better gas mileage and runs better it would be worth the extra 20 cents.