jdcowboy

It does sound like you are a little low. Although, there are many things that factor into fuel mileage like, driving habits. City driving is not always the same. If you never get out of town and you are constantly in stop and go traffic your mileage is going to be much lower than some one like myself that lives in a town of 80k people and has very little grid lock. I find that I get 20 to 21 mpg around town when I have very little hwy mileage. But just recently with our cold weather, I have dropped off to 18mpg. I hope it just the cold weather, and letting the car constantly warm up. Also I have a stage 1 kit in mine. And yeah it is fast....or a beast as they say. Mine going on flat, dry pavement rolling at 25 to 30 mph, and nailing the gas will yield a roasting of the tires, when traction control is off.

OKIE SS

I've been tracking mileage on my 2008 SS since I bought it in September. On a highway trip from southern Oklahoma to Kansas City I got 28 and 30 on the highway running 75-80 most of the time on cruise control and A/C on. Got 25 while in town for two days and got 25 in town locally when I got back initially. Last calculation was down to 22.5 with mostly short trips in town driving. I don't put much heed in the driver information center so I do my own calculations on a spreadsheet.

I don't really drive mine that much as I'm retired and only get gas about once a month and that's between 9 and 12 gallons but I have noticed a drop in the last three months:
9/29 - 28 mpg (the leg home of the KC trip)
10/23 - 25 mpg around town
11/25 - 21.5 mpg around town

The last fill-up mileage might be attributable to learning how to use my remote start and letting the car warm up until vacuum is built up (separate P/B issue common to 2008s) but even then it only idles for a couple of minutes tops on first start.