I'll play devils advocate here, if it were my car I wouldn't go through the trouble of trying to fix it. How many cars have locking gas doors, not many, if you live somewhere where you're worried about someone stealing gas out of your car, then you have bigger issues, in other words you need to move...lol!!

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2002 X5 4.6is
1999 C5 Corvette
1992 Mitsubishi 3000GT VR-4
1994 Kawasaki ZX-9R
2005 Mazda 6 Wagon (Wife's)
1991 Mitsubishi 3000GT VR-4