I have had the pleasure of driving both vehicles, and they are pretty different beasts, yet both offer all kinds of fun. The c43 is more along the lines of an m3, its power to weight is good, and its raw acceleration is amazing. Since it is a smaller 4 door, its a lot easier to throw around in the turns. I would classify it has a hard edge weekend racer. The E500 (I actually drove a 500E) is a bigger sedan (obviously) Its power delivery is smooth as silk, but I wouldn't call it a rocket, more like a train that gains velocity at unsafe speed. It is a grand tourer in the highest fashion. The car feels like a luxury vehicle, and tightens up pretty nicely around the turns. I prefer the 500s staid interior to the newer button and plastic happy jobs on the c classes (which is odd, considering I love gadgets) But, as far as thrill goes, the c43 wins for 2 reason. A.) it is a slightly more capable sports car (acceleration and handling are key in my decision) and b.) People actually recognize a c43, nobody knows what a E500 is, and I guess its part of the thrill to have every teen in town try to race you.... (It might get old after a while, but hey, im 17, and its still all fun and games...)