Flip Top Gas Cap Conversion

4mulaSvaliant would be the person to ask, the link above is to the thread where he was selling them. I think he makes a production run when he gets enough orders if he doesn't have any on hand.

Modifying the car is exactly as I described it above. Its as easy as drilling 3 holes, or as hard as drilling up to 7 holes, countersinking and threading. Up to you. They fit pretty well, although if you're a real perfectionist you can trim the adaptor a little so the cap sits a bit more level, the filler neck area on a Duster is slightly angled, so the cap will be too unless you shave the adaptor down a smidge.

And yes, I used machine screws on purpose. That way there's a nut on the back, and you need to open the trunk to remove the cap and adaptor. So if someone wants to steal them, they have to work a little harder.