The F90 M550i xDrive is the sleeper M car—$45K gets you 523 hp and nobody knows what hit them
The M550i trades the S63 twin-turbo V8 for BMW's B58 turbocharged inline-six, but keep that quiet. With xDrive, adaptive suspension, and that M Sport chassis tuning, it does M5 things without the M5 price tag or the attention. Clean examples are finally hitting the used market.
The M550i is what happens when BMW's marketing department sleeps—a car good enough to make actual M5 owners uncomfortable at a stoplight, and nobody's talking about it because the badge says 550, not M.