Redbull does. They have two actually.
http://www.fuddymuckers.co.uk/gallery/redbull/web_IMG_1701_s.JPG
I am on LSU wakeboard team and we recently had a railjam that redbull sponsored.
I looked over this thing in some detail and got some info.
It is on a k-5 frame, has a corvette engine swapped in, the one i saw rolled on 35 BFG KM2's, has chevy tahoe leather seats. It has two rear mounted jerry cans that flip up and are actually waterproof speakers. It has two large flat screen LCDs (about 40") that are mounted back to back the raise up from the center of the vehicle and then rotate around sticking out of the roof. The back trunk folds out and exposes a place for two to stand and have a full turn table (for records an ipods) infront of them. It also houses other speakers and an onboard generator.
We had the winch for the railjam attached to the hitch on the back of this beast. Pretty sick rig. I was talking to two of the redbull reps and he said that this was the vehicle the gestapo drove around during WWII. (just going off what he said, not sure on the validity of that)
