I know there's a survey area somewhere on this site for the great gas controversy, but since I'm not sure where it is, I'll post my unscientific info here. For the first 1000 miles I used regular. Then I zeroed out all the trip settings, etc., and drove for about 1700 miles at an average speed of about 38 mph using only regular. Result? 23.0 mpg. The dealer told me I would get max performance with premium (don't really care about that - more interested in mileage), and that he had several customers who found using premium increased their mileage by enough to more than offset the price diff. of the gas. So, for the next 1700 miles I used only premium. 38.3 ave mph, and....23.0 mpg. Lesson? I just spent about $25 finding out that premium makes no difference.
FYI -
gibby26
FYI -
gibby26