I recently purchased a 2002 DTS. The vehicle only had 3900 miles and had been sitting for a while. Before selling the owner serviced the car. I am happy with everything except the fuel mileage. To say the least it is terrible. No where close to what was posted that this car should get. I feel I am a conservative driver and have never had trouble with any previous vehicle not getting what the manufacturer posted. I had the car serviced and was told all looked fine and there was nothing that could be done. Is this normal? I do good, pampering the vehicle all I can, to get around 10 MPG locally and maybe 15 to 16 on a longer trip. Any suggestions? I am about to the point of selling the vehicle. I might as well keep driving my large SUV. Actually I get just as good gas mileage, if not better.