i have a 2007 300 c and its killing me at the pump!! i can literally watch my gas gauge drop .when i accelerate.but I LOVE THE CAR! ..

 

If the sending unit is at the front of the fuel tank, acceleration will slosh the fuel to the rear of the tank and the gauge will drop a little. Try parking facing down hill and see if it goes up. Driving habits can have a major effect on gas mileage. If you're a lead-foot driver, expect to use more gas.