About the gas gauge. How come that the tank will not fill up all the way? I usually fill up with just under half left, (makes it seem cheaper), and the guage usually only goes up to 12 or 14. A few times I have been able to squeeze enough in to fill it to 16, but not usually. Also, the gas gauge is pretty tempramental. Some days it won't go down, then others it will go down like a whole needle length. Some days it even goes up! Really unnerving. I usually get about 245 to the tank according to trip computer,but I do 99.99% of my driving in the stop-and-go city so that cuts my gas mileage down dramatically.

Any ideas?

 

The sending unit might not be accurate.
I think there is a calibration the Dealer can try.