The only thing different between 2 octane ratings of gasoline are how quickly they burn. Yes, the higher octane can have more advanced timing, but that just starts the burn earlier, letting it burn slower. The energy content of regular gasoline is actually slightly higher than high octane.
I agree with the person who stated that it may be that the premium gas doesn't have as much ethanol added to it, although that's probably hard to be sure of. I know for sure that here in the Pacific NW, they put a lot of crap in the gas during the winter months like MTBE, and 15% ethanol, which really hurts mileage.
Either way, I'm vastly exceeding Chevy's estimates for mileage, and I don't even have the turbo motor.
I agree with the person who stated that it may be that the premium gas doesn't have as much ethanol added to it, although that's probably hard to be sure of. I know for sure that here in the Pacific NW, they put a lot of crap in the gas during the winter months like MTBE, and 15% ethanol, which really hurts mileage.
Either way, I'm vastly exceeding Chevy's estimates for mileage, and I don't even have the turbo motor.