What's the best sleeper car, or best car to turn into a sleeper car?

Welcome back to Questions of the Night. Sorry for the one night hiatus. You guys seem to be enjoying this and contributing, so I'll try and keep it going. Leave your feedback in the comments.

My choice is not necessarily a sleeper car from the factory, but I would turn it into the ultimate sleeper. I would get a new Mercedes E63 AMG Wagon, the one with the AWD, because it's faster off the line. I would then de-badge it completely, and install E250 Bluetech badges. I would also paint the brake calipers black, as they come in red, and I'm not sure, but I might remove with double exhausts as that gives the rest of it away, at least to someone like me. I think the Germans see a market for something like this because of the rumored "Business Package" that deletes all the go fast parts on some AMGs.

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