Dare I say it, but the W204 C63 is one of the only performance cars I'd consider buying without a warranty. Post 2011 or after earlier cars had their head-bolts replaced, these cars have proven to be virtually bulletproof despite some owners consistently abusing them and, they are pretty inexpensive to run in comparison to any competition.
However, there is absolutely no way on earth I'd run any of these late performance cars with turbocharged engines without a warranty. M4/M5/M6, GTR... no thanks, especially BMW's due to my horrific past experience. I think it's too early to say about the W205 C63 and perhaps W212 E63 is proven, but I don't really know.
The W204 C63 is a brute that sits well within its comfort zone, even tuned. I have found that all of the high performance turbocharged cars that I have owned are fairly high strung from the beginning and dare you tune them, then prepare to see some weak spots elsewhere (plumbing, sensors, fueling, ignition etc). You have to pay to play, that's a given, but these days I'd rather do that on a car that costs under £20,000 with no manufacturer scrutinising my car in an attempt to refuse a warranty claim. In some cases, what the extended warranty will cost you per year will often cover any additional work that you need during that period anyway. The one time that a warranty pays for itself is generally if you blow something up.
Anyway, what would attract me to a C63 is a maintenance plan as it's a nice touch not having to pay a few quid for an A Service (plus plugs eventually) or £700ish for a B service for a couple of years.
