I have a new key fob for a 2012 MB E-class that I bought from MB for a spare. I am looking to purchase a 2012 MB CL550. Can I get the fob reprogrammed to the CL550?
For the most part once Mercedes keys are programmed they are burned to that programming (if you ordered from MB then its pre-programmed already).
While it is possible to unlock the key and reuse it. It is rare and not many have the equipment to do this however. Mostly unlocking is used by locksmiths who want to refurbish used keys for use later. Locksmiths also do not like to use outside of their own supplies because we do not know of its origins. Even if you found someone with the equipment it would likely costs you more to unlock and then program, then to just get a new fob from them all together.