I have a fairly new 2006 XJ8 but the driver's door rubber seal is falling apart. Anybody know why this happens and how much would it cost to replace it?

 

My guess is that sombody wiped that seal down with mineral spirits, lacquer thiner or worse. Probably on a regular basis.

No clue on price of door seal but it is a Jag specific item and as such will not be cheep. Just for giggles, start with www.welshent.com and then move on to your dealer.

Do let us know the price an source you end up with and, if you can find out, the cause of the seal rot.

 

Assuming the weather strip on the door and not the body frame:

 

The poor seal is on the car body, not on the door. Strangely, I had the same problem on a 1999 XJ8 which I bought in 2003 but the dealer had it replaced at no charge before I took delivery.

 

I know of a few that grab the body frame to inter or exit the car and they tend to tear the weather seals.

 

The seal on my car's body is also worn. When I purchased my car, the salesman guessed that the seal-wear was caused by the seat belt nipping the body's seal after being released from secure position and snapping back into its 'holstered' place.