The M3 has next to no low down grunt especially for a v8 compared to the C63
As for difference between the 204 C63 pp vs the ppp
PP was alot furmer suspension slower gear changes (not a patch on the DCT) and quite abit slower as on paper its only 457bhp ,you did get the LSD as standard though I had the M3 after that car and hated it
The 204 ppp is better interior quicker gear changes alot more power (mine was 503bhp ) totally standard I had the LSD fitted the 1st week i had it
They were both nice car's and tbh I wasn't keen on the w205 until I drove 1 yes the saloon looks abit boring but imo they are way ahead of the W204 Which I thought id never say ,then I got the C63s coupe which is another level up again and in-between all that I had the SLK55 AMG which I enjoyed aswell sounded unreal with the xpipe