The V10 M5 will surely go down as one of the most bonkers cars in history.
It feels like an event every time you get in. That feeling is probably due to the character of the gearbox and engine. When it comes on song past 4000rpm, it makes you appreciate the engineering of that car. Don't run without a warranty, though, parts are eye wateringly expensive.
I've known two people who've had one, and both faced bills of £2-3k each in short ownership.