bought my c400 last year at the end of april and have driven 40k miles so far, so it's currently sitting at about 62k miles. The only things I have done so far are front rotors and pads, rear pads, new wheels and tires, oil changes every 6k miles, transmission fluid change about 10k miles ago, and about to do front and rear diff fluid and spark plugs. The only issues I have had were the capacitor thing went bad (taken care of warranty), the transmission was very jerky after i bought it when it downshifted from 3rd to 2nd, I had the software updated under warranty (still somewhat jerky), and I had one of the led door handle that died (replaced under warranty). It seems like there's a bug in the ecu because the turbo doesn't kick in for like 5-7 seconds from time to time (randomly, at about 30% throttle) but since I can't duplicate it willingly, I just don't worry about it.