If it's good enough for Sebastian Vettel to buy then it certainly gets our attention.
There are plenty of fast SUV/crossovers out there, and it's true that some of them are faster than the Infiniti FX. BMW has a couple of these, Porsche has one too, but these have a downside. If you pull up to your kids' school in something with a foot-long "Turbo S" badge across the liftgate and a front end which is clearly at least trying to look like a sports car, other parents will start to form some opinions of you. They won't want their kids hanging out with the speed freak's kids, and eventually your kids will end up friendless outcasts.
They'll grow up with weird antisocial hobbies, like making life-size statues of Lady Gaga out of parts of dead raccoons, and trust me, you don't want that. Ok, so maybe that won't definitely happen if you buy a Cayenne or X5 M, but discretion can be an important quality in a family car, and that's why the FX is such a brilliant hidden gem. Part of what makes the FX discreet is the Nissan Murano. They are similarly-sized crossovers from the same parent company, and it's natural to assume that the difference between the two is largely badging and sheet metal.
The Murano is a nice enough vehicle, although nothing too terribly exciting, and it would seem that the same assumption could be made about the FX. But in fact the Murano and the FX are built on entirely different platforms, and the FX has some serious sporting pedigree hidden under that crossover body. The Murano is built on the same platform as the Altima, which like the Murano is nice enough without being particularly sporty. The FX, however, is built on the same platform as Nissan's 370Z sports coupe. Infiniti worked hard to preserve as much of the Z-car's sportiness as possible while transforming the platform into a higher-riding four-door vehicle.
A range of engines are offered as well, but if you're looking for the maximum sporting potential from your crossover, then you want the 385-horsepower 5.0-liter V8 power of the FX50. It can hit 60mph in 5 seconds even, and run the quarter mile in 13.7 seconds. Handling is good as well, and it can pull .87g on a skidpad, an incredibly high number for a crossover. Even other sport-oriented crossovers rarely have the kind of sports car underpinnings which the FX has. This does, unfortunately, translate into a comparatively stiff suspension, and rather limited cargo capacity as well.
However, it performs brilliantly, and is even relatively cheap when compared to other performance crossovers. The driving feel is surprisingly carlike, feeling much more like a sport wagon than a crossover. This is one of the main selling points of the FX50, a Cayenne Turbo S or X6 M would destroy it in a straight line, but you'll have at least as much fun, if not more, throwing your FX50 into the turns. Add to that the fact that the FX50 costs less than half of what an X6 M costs, and a bit more of the all-important discretion gets added to the Infiniti's column.
The other vehicles in this series are fantastic, but with the exception of the long-extinct Nomad, they aren't really mainstream vehicles. Astronomic prices, huge wheels, painted brake calipers, about a dozen tailpipes per car, these vehicles are aimed at hardcore enthusiasts, and they are the very definition of a niche product. But the FX50 isn't from a special performance division of Infiniti; it hasn't been lowered, or given skirts or extra vents. It's just a version of the FX with a bigger engine, but none of those extra bits which carmakers use to drive up the price on performance models.
There's a lot to be said for this, both in terms of price and social advantages. No less an automotive enthusiast as Sebastian Vettel has an FX50. Infiniti did come out with a Sebastian Vettel edition of the FX50, but Vettel hadn't even been approached about the idea of this special edition until he had already bought the car for himself. This being the reason why Infiniti decided to make the special edition out of the FX50 rather than a more pure sports car like the G37. The Vettel edition, it's true, is not quite as subtle as the standard car, but it's still a good midway point between the regular FX50 and BMW's M cars.
If your social standing and bank account can take the bigger hit, you'd probably pick something else over the FX50, and that's fine. The FX50 can remain one of those best kept secrets. But you'll still know the FX50 owner when you see him, he'll be the guy who shows up to the school to pick up his well-adjusted kids with a big grin on his face. As far as he's concerned, you can keep your X5 M and your weirdo children.