The past couple of tanks I've gotten to almost 30 mpg, but I don't think I can get much higher than that with DC beltway commuting.
My overall average is 28 MPG. Winter does bring the mileage down, especially if it gets really cold. My worst mileage was a 23 MPG tank, but that was with fighting to get out of snow for an hour and deicing the car. Se la vi.
~X~