I filled up my gas tank this AM, drove 50 miles and saw it was nearly reading empty. I added more gas to the car, but could only put 1.5 gallons in before the machine shut off. I also observed that the fuel gauge moved a lot while I was driving (a little movement up and down hills is understandable, but the pointer fluctuated and stayed toward the lower 1/2 of the gague. I drove mostly freeway miles, always fill up the gas tank to the top, and changed my fuel filter last week. I suspect that the problem lies with the fuel gauge and not the fuel system. Thanks in advance.