Originally Posted by cbdallas
It won't hurt anything but your wallet.
I put about 11 gallons in the tank of premium. The premium costed 35c more than the regular at Exxon at the time. Thats $3.85 more for the fill. Considering it improves performance some (power and mileage), I think it's worth it - especially if not using premium all the time.
Would you still fill up with regulare if gas was $2 a gallon? Don't think so :)