BMW M6 from the 80's. One of the best cars BMW have ever made. Had a chance to buy a mint low mileage one off a friend in California once. Should've done it... Other than the 7 Series from the late 90's its all been downhill on the design front from the boys in Bavaria since.
Just released photos of the new Audi Quattro concept have hit the interwebs and I am a fan. The concept is muscular without looking outlandish and has all the build quality one can expect from the Germans.