I spoke to a friend (who is a mechanic) about this. He said that you can run regular gas on high compression and turbocharged engines. It will run like crap at first until the ECU adjusts timing and fuel to keep things save. But performance will go down, as well as gas milage. So the money you save at the time of fill up will go down the drain because you are getting less miles per gallon. He said it won't save any money and it's not worth the risk.