www.madmaxmovies.com

I believe the reason JXL was chosen for Fury Road is because of a common trend in recent movie soundtracks which are very percussion driven (The Dark Knight Rises, Man of Steel...).
JXL has been working with Hans Zimmer for a long time and I think he's the driving force behind percussive elements of his/their soundtracks. There's a little 'making of' on Youtube which shows how they assembled a giant drum circle consisting of 12 drummers grooving to Zimmer's score for Man Of Steel, JXL being the man who patched it all together.

It's most likely that JXL will collaborate with a more 'traditional' composer for this film much like he has before on TDKR and Man of Steel.

Small update but according to JXL's Twitter he'll be in Sydney the first week of March to officially begin scoring Fury Road.

Collider has an interview up with Junkie XL talking about his recent scores released for 300 and Divergent and touches upon Fury Road:

One of your upcoming projects is with director George Miller on Mad Max: Fury Road. What’s been your reaction to Mad Max so far? How did that project come together?
JUNKIE XL: I’m actually working on Mad Max right now. We’re finishing in two months. It’s a fantastic film. I mean, I can’t really say a lot about it obviously because it’s all hush hush. I can tell you that my experience with George has just been fascinating. We’re talking about an Oscar-winning director and he’s been around for so long. The conversations that we have together are really tickling my imagination. He pulls very deep inside of you to get the best that’s possible out of you. I find it a fascinating process. I got the movie because he heard the 300 score.

What kind of sound are you going for with the new Mad Max? Are there any special instruments you’re going to be using?
JUNKIE XL: I’m not allowed to talk about that, but it’s going to be a very interesting one. (Laughs)

Did you get to spend any time on set?
JUNKIE XL: No, because everything has basically been shot. They have some additional photography to do, but I haven’t been there which is great. I know, for instance, that Hans (Zimmer) has been multiple times on sets of directors that he got really well befriended with. He just came down to check out what was going on, but I think it has to be the right film to do that, and also you need to build relationships a little more. For me, it’s still like a fairly young career and I think as I go I hope to be in that same situation at some point.

http://collider.com/junkie-xl-mad-max-3 ... interview/

Interesting. So they began work on the score at the beginning of March and will continue through to May. According to Junkie they're going to be doing more additional shooting.....?

Could be a stretch but is this our first listen to some of Fury Road's score:
http://instagram.com/p/nW8B2ZABvw/

Well, he's got #filmscoring attached to the post, and since he's already stated that his time now is entirely dedicated to FR, I would guess that it is indeed for the film.

The first moment it sounded a bit like the opening scene of MM2. He might have put some influences of the old movies in it.

Looks like that sample was from FURY ROAD and I found he has a couple more up too:
http://instagram.com/p/nrVLdfgBhB/
Pretty ominous piece with brass instruments

http://instagram.com/p/nWAGCbgBsy/
http://instagram.com/p/mohMc0ABrd/
String samples

These sounds are definitely influenced by the music that is playing during the narration scene at the beginning of RW.
I'm very curious how this will sound in the finished film.

Sounds very inspired by Brian May's work on the Road Warrior. Couldn't have asked for more.

For me, two things are almost more important than the stunts : the story, and the music, the music and the music !
If the music is great, you can watch the movie again, and again and again, like when you play a record you like.