I'm on my 4th 300 Diesel. All the luxury items can mean trouble, but in all of it, if you get the service manuals, they are worth it. It has the "Benz" feel when you push a button and get that response. I had a great amount of frustration with the climate control in my first two cars. But I got the diagrams and traced it down. Not too much money...GREAT deal of satisfaction when I dialed in the temp and it all worked. I've never had a window problem that wasn't a dirty switch. Perhaps I've been lucky, but then again I love to spend Saturday afternoon at a good "U-pull-it" yard and get extra parts.
Good luck with either car. There is nothing like the feeling of riding behind the "star"!

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R Talley
88 BMW E32 735i (make it go away)
95 Volvo 960 "Inga" (valve problems)
95 Nissan Maxima (the indestructible)
89 Ford Ranger XLT (ugliest truck in the South)