A fellow Passat owner and with black leather interior! I use 303 on the interior of my Passat at least every 6 weeks, it really brings it to life with a rich, deep black finish. First, I wipe down all the vinyl and plastic with a solution of Dawn and water, and then wipe down with water dampened MF towel. After letting it all dry, I apply 303 with a foam applicator and let it soak in for a couple of minutes then I buff dry with another MF towel.
For my leather I usually just clean with a water dampened MF towel and then apply 303. At least twice a year I'll deep clean and condition with Lexol. For in between cleaning I've got some einszett Lederpfledge that I'll use. I want to try out the Woolite solution when I use up my Lederpfledge! I wouldn't hesitate to use the 303 on my leather seats, it works beautifully. There is a bit of a shine let but it isn't glossy at all. I like the peace of mind I get, I know that I'm protecting my BLACK interior from sun fading.
Just a few comments to conclude:
I wouldn't rely on 303 as a cleaner. I think it might have a mild cleaner in it but always do the cleaning yourself that way you know it's clean to begin with.
You may notice some blotchy spots after a bit of time, especially around the glove compartment, seems that area just soaks it up. Usually it will buff out and be fine. Other than the mentioned area, I don't notice any blotchiness on the dash or seats.
Check out
www.303products.com for all the information you could need on 303. There is a lot of info on application and the like. Here is the link on 303 use on leather,
http://www.303products.com/techinfo/leather/leather.htm.
Good luck and enjoy the Passat
