GT5 XL has all the updates to 2012 and makes the game much easier to play than the original year old disc.
You can buy tyres and most parts at the race courses now, and it's easier to tell the power of each car in relation to other cars. You can even see if you already have the car in your garage that your contemplating purchasing. But, If you buy this GT5 XL version of the game, you will not be able to download the purchases you have made at Sony Entertainment if you live in Europe.
So No Car Pack 2 and 3, Racing Car Pack, Track Pack, or the Speed Test etc.
Taken from Sony Information Sheet :-
< If a user who owns the North American disc purchases the DLC's (Down Loadable Content) with an account that has a UK address and location, they will not be able to use the DLC using the North American disc. >