Terrible Mileage in the city-15 mpg!
 

Really bad! 15 MPG! Cant figure it out! Its the sport package, bought it in early august. I have almost 2k miles on the engine, mostly highway miles from two family vacations up the California coast before my son returned to school. So here is the history. Highway miles were great during break in. Up to 40 mpg at times. Since then, my only real driving is around the city. Mostly my son to and from school. He's in 6th grade and not heavy. Anyway, according to the computer, my usual average is 15 mpg! My main reason for posting is to see if anyone else has experinced this. I am a fair mechanic, so engines are no mystery to me. I am a conservative driver with a light foot. I use regular octane, chevron 87.
Any ideas? Anyone else had/have this problem? I guess I'll call the dealer soon. Just a hassle because he's 50 miles away. In Los Angeles traffic, it might as well be 200!
Any input is appreciated!
Thanks,
John.

I am on my third tank fill and all my driving is city.

Gauge showed 24.5 and 25.5. I filled up and calculated it from the gallons and trip gauge and I was within 1 gallon. (23.5 and 24.5).

For my first tank, I had the AVG MPG display up and drove like a golf cart. For the second tank, I had the Range display and drove it like what I would consider normal. Funny thing is I got better mileage when I wasn't paying attention to it.

Have you tried comparing actual gas usage with the odometer to see if it matches the display of 15?

Thanks for your reply.
So, here is an update. I'd forgotten I reset the on board computer about a month back after a loose fuel cap brought on the check engine light. I disconnected the battery to reset, and soon there after began noting the low mileage. So this past weekend, on a hunch, I did a second reset, then hit the freeway for about 45 minutes. Mileage was decent at 29-34 mpg. This morning, took my son to school, and the computer dropped from 26, to 21 mpg, and thats where it the # now sits. So I conclude that, after watching the computer performance closely, it requires some distance to guage accurately? I hit many stop signs and neighbrohood speed bumps on the two mile drive to my sons to school. So maybe the speed is just not consistant enough for the system to guage mileage? I am clocking the mpg manually now, so I will report my findings. I dont drive much though, so it may be a couple of weeks.
Thanks again for your reply,
John