My 04 xjr was making a mystery noise that sounded like creaking floorboards of an old house. At first i thought it was the suspension but fogured out it was the door hinges. I usually dont open the door all the way but i did today and hesrd that familiar sound. Apparently when fully extended or fully closed ths hinges and the little plastic arm midway between them flex and while the car is moving and flexing over bumps it causes the creaking noise. I sprayed them with silicone spray and worked the doors back and forth and the sound is mostly gone. All 4 doors were doing it so now that ive done this the car is tremendously more quiet driving around. I can still hear i little of it but im going to spray the hood hinges when i get home just incase theyre doing it too. This has probably already been solved by other members but i thought id put it out there.