I went to a local shop that mixes and matches paint based up on the paint on your car. It took the Gentleman about 2 hours to exactly match my color. I needed to touch up the area where the right and left hardtop locking studs enter the body. He did a good job. He only charged me $25- for a 5 once jaw of touch up paint.
Recommendation, perhaps ask a Benz, BMW or Porsche dealer where they get special paint prepared this might be one way for you to get a good match up.