If the other wood is good, DON'T STRIP it. Most likely it looks lighter because the factory finish has become slightly "milky" from UV rays. Take it out of the car and wet sand it starting with 600 grit, working up to 2000 grit, clean it throughly than rub it out with rubbing compound and finally polishing compound then a coat of good wax. The color will look much darker. Basically you'll be treating it the same way you would tired paint.

Use plenty of water during the sanding steps but be careful about getting it under the edges of the factory finish, it has a tendency to lift if you do. Also, small steps in sandpaper grit size is much preferable to big jumps.

If all else fails the factory finish can be stripped with "aircraft" stripper, available at a lot of auto parts stores. My local Autozone has it. Even so it will work slowly and will take several applications to remove the finish. Put it on, then leave it overnight (12 hours). It won't work the way you are used to. After 12 hours the finish will look "crystalized" and can be scrapped off. Go slow, and don't use more than neccessary.

NEVER SAND. MB veneers are very thin. You'll go through to the backup wood very quickly.

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire