If you take it to a BMW or Mercedes dealership go to the body shop and ask them to bring out their paint match tool. It's a little digital camera thingy that will create a paint code for your car that takes sun fade and oxidation into account. Ever see when a person gets their fender re-painted and it looks darker/wetter than the rest of the car? It's because the rest of the car faded. Factory touch up paint is only good for about the first year of your cars life, after that you need a custom blend. My brother works for Roger Penskee's BMW division in his paint shop...you should see some of the gadgets they have.