For starters, I do not have any key problems right now, but.....I want to stay ahead of any in the future. I have a new IR Master Key (flat key, no IR remote) that I purchased at my dealer. It appears to have a chip and I believe it will do everything other than unlock the doors with infrared. There is a key maker in town that can source an aftermarket key for $450, but I need to talk to him to see exactly what I get for that. Likely no infrared, but not sure. I haven't used the flat key, and it's still in it's plastic package, and I'm afraid to have a key guy fooling with the car although they were recommended by the Benz dealer and have the keys on hand. Evidently they know what they are doing. The goal is to have a spare full function flip out key, with infrared if possible. Comments or recommendations?