Found this article in the Chicago Tribune.

Bottom line is what we already know. Using regular gasoline in a car that requires premium will not harm the car, but you will get reduces performance and possibly reduced gas mileage, which may cancel out the savings of using the lower grade gasoline.

 

can you say PING! I can't imagine running a lower octane in our car wld be good for it or even safe. Not something I would chance for the price differential per gallon.