Is you car all stock? We run 89 in ours 80% of the time - plus you will see a slight gain in MPG with a lower octane as long as you are not heavy in the pedal. I would NOT run 87 in the car however - but 89 or better is what I would do. It's always GOOD to run a tank of 93 however every now and again to help flush some deposits out. (You can do this when there are no kids in the car or wife)yes automatic. So it seems like I am in the norm. Do you HAVE to run 93 in this thing? Previous owner only ran it so I just followed suit. I barely go into boost anymore. Always have 3 kids in the car.
No that's piss poor, waht plugs are you runing ( only NGK BCPR6ES) BAd Temp sensor, O2 sensor and MAF ( AMM) can all lead to poor mileage...I was going to ask the same question, you've cleared it up for me. I use mostly 93 octane Shell (or other Top Tier) and get 19-20mpg on my daily commute of 15 miles one way. 10 of those miles are highway at 65-75 and the other five is stop n go.
And yeah I early on realized this car is heavy, just the weight of the doors and trunk lid are considerable.
It compares unfavorably in terms of mpg to my previous car which was a 2006 Chrysler 300 Touring, with the 3.5L V6 weighing about 3850 lbs. It could get 22mpg on the same daily commute. But then I enjoy driving this car a bit more ;-)