I know the car is supposed to get ~ 27 MPH city and freeway combined, but I'm not seein it thus far. I have an '05 LS automatic and it's really low. I filled my car up to half a tank yesterday; it was nearly on E when I put in 3.45 gallons. That took it up to half, so I'm assuming the gauge is off... Not sure, but doesn't it have a 10 gallon tank? or is it 12? Not sure really...

Anyway, I drove about 16 miles in some heavy traffic and it used nearly a quarter of a tank. So between 2.5-3 gallons used for 16 miles? But since I had roughly 4 gallons in it (at least to my knowledge), which brought it to the halfway mark that'd be about 1... Still, 16 mpg is super low from what I've read online..

Could it be that I have an 8 gallon tank? That'd seem rather odd to me, being so low...

Is there some way that the fuel gauge could be off?

Thanks for the advice!