Whats the betting that this is a paper argument based on no actual real life experience?
Just go and sit in both of them! You may not get it, as we have clearly different opinions and expectations when it comes to cars, but you probably would agree. I personally know people with both of these cars, i will not pretend that my experience of either is comprehensive, but it is enough to say that i PREFER the C63 to the M3 based on real experience. The Mercedes has an interior more in keeping with what i like, and is overall a nicer, more prestigious car in my eyes.
Thats fair enough, I don't agree (with your saying the M3 is half of a C63) but that's part of life!
My issue with the C63 is that is just seemed to compound what I always disliked about Mercedes, particulalry main market AMG's. I'll try and explain.
This time round I think AMG had a real good go at defending their perceived achillies heel, handling, to use a broad expression. For years they have produced fine cars, some engineering masterpieces IMO (SL55 AMG is one of my favourite all time cars) but they have always played second fiddle to BMW when it came to driver interaction, feel and real life "pace".
It's clear from reviews, tests and customer feedback that they have tried to make improvements and in some places they have. But again they seem to have prodiced a car that when pushed to the limits (why else would you have one?) is still a bit of a handful and frankly doesn't cope as well as a car of that ilk should, given it's aimed more at the M3 than any other AMG I can recall.
That is why the C63, which will comfortably have the edge on an M3 in a straight line, still seems to lose the plot when it comes to testing side by side on a track, or even on real life A Road conditions.
I genuinely think if AMG had concentrated their efforts away from using massive displacement to get the huge power/torque, they could have possibly had a much more balanced package to challenge the M3 with.
So, whilst there's many things I like about the C63, I do not see how you can say it's half the car that the M3 is in all area's but in particular, the important one in this sector of the market, getting from A to B quickly and in comfort. M3 takes it every day IMO.