Figure out who it belongs to (do Bugattis have glove compartments), figure out where I am, try to remember what I was doing before I was unconscious in an expensive car, fantasize about what I might have been doing before I was unconscious in an expensive car.
Depending on how that turns out, find the person, find the keys, leave the car OR take that thing for a spin. If it has no owner or an owner that isn't me, it's going to be hard to explain, so I'm not sure about just keeping it.
If it was mine to keep, I'd probably sell it and get the most irresponsible computer money can buy. Otherwise I'd probably just crash it and be sad.