AMG has stated that they will build an AMG version of every vehicle Mercedes makes. They signed this agreement with Mercedes a couple of years ago. But for some people who don't want to be seen in a regular AMG car and demand something more, AMG makes it happen for them. Did you guys know that AMG can customize a regular AMG car that's bought at a dealership? They will remove the speed governor and do engine mods for those who demand to be different. Well, the Germans anyway. US buyers get shafted.
http://www.mercedes-benz.com/amg/default1.htm
CORRECTION: The SL 740 I talked about wasn't a 740, but a 730. My appologies.