Isn't that like going to a nice restaurant and asking if you can bring your own drinks from home? I can't believe people still ask this; you're driving a LEXUS! You paid SEVERAL thousand extra dollars for your car when you could have gotten by with an old Honda, and you want to save a couple cents on gas with the possibility that you'll damage the car?

I wonder if gas would be any cheaper if I just bought my own oil refinery and a small country in the middle east...