Until the F90 BMW M5 is officially on the road, the BMW M550i xDrive will continue to hold the title of the fastest 5 Series ever made. That’s right, it’s faster that even the F10-generation BMW M5 30 Jahre, the previous fastest 5er. Admittedly, it won’t hold that title for long, as the new M5 will hit American shores in a few months and strip the M550i of its crown. But even once that happens, the BMW M550i xDrive will remain a brutally fast 5 Series and one that’s very much worth owning.

The only real problem with the BMW M550i xDrive is its perception. Thanks to the “M” in its name, enthusiasts and customers may be expecting something a bit different, something a bit harder-edged. But the M550i isn’t hard-edged at all. Automobile Magazine recently spent a week with the M550i finding out just that.

Step into the BMW M550i and you’re greeted with a luxurious cabin. Instead of the sport seats and carbon fiber you’d find in a proper M5, the M550i sports sumptuous buckets and wood trim. Just one look at the inside of the M550i and you’ll soon realize that it’s an entirely different animal from the tire-eating M5. It’s more refined, more relaxed in it approach to speed. Whereas the BMW M5 is loud and shouty, the BMW M550i is a calm and quiet cruise missile.

Don’t think that means it’s boring, though. It’s brutally fast, thanks to its 4.4 liter twin-turbocharged V8 makes 456 hp and 480 lb-ft of torque. Despite not being a proper M car, it can accelerate from 0-60 mph in under 4 seconds (around 3.9 in most tests), which is about three tenths of a second faster than the previous M5. It’s also capable of handling some twisty roads. It might not do so with the verve of a proper M car, and it lacks the steering feel to really feel what you’re doing if you wanna drive 10/10ths, but it does have incredible grip and dynamic capability, enough to entertain during a fun stretch of road on the commute home from work.

But the rest of the time, it’s calm and quiet and relaxed, allowing you to sink into its brilliant cabin and listen to its superb Bowers & Wilkins surround sound. All the while knowing that at the squeeze of your right foot, the rest of the world can disappear behind you in the blink of an eye.

[Source: Automobile Magazine]