Early this year on the very first fuel stop after picking up my 05 I left my gas cap at the pump. http://www.lotustalk.com/forums/images/smilies/facepalm.gif
I got a generic one which kept me from getting evap MIL codes, when I got home I did a bit research and found many Jaguar caps are compatible. The Jag dealer is about two miles from my house and the Lotus dealer is quite a bit further. So I went to the Jag parts counter and they pulled a couple from stock so I could match them to friends cap I had borrowed as an example. All three matched the 1/4 turn key-way and one of them had a tether. I thought the tether might be nice and was worth a try to keep this from happening again.
To install I looked around for an anchoring point and saw the rubber nub which keeps the door flush with the bezel and it as just about the right thickness. I removed the rubber nub under the fuel door and zip tied the rubber end of the tether to the now vacant hole, the fuel door sits flush to the bezel as it did before.
I've had this on for a few weeks and I'm happy with it overall, and now I don't have to worry about leaving my gas cap at the pump. Although I doubt I would now anyway. Hope you have found this helpful.