190E: I can drive it without worrying about shopping carts, dings, dents, etc. and I can gradually restore my 300D without worrying about putting too many miles on the diesel.

300D: Learned the habit of "looking back" at the 300D when it is parked, and making sure to get a seat in a restaurant that gives you visibility of it

My 300D is more of a leisurely drive, keeps me out of trouble. My 190E is more of a spirited drive, keeps me ahead of trouble