2009 Infiniti FX50 vs 2009 BMW X6 xDrive50i

John Roe

That's a lot of money for a large truck with radical styling and only four seats. BMW knows this and acknowledges that the X6 is a low-volume, niche-market vehicle. The company expects to find homes for fewer than 10,000 X6s per year, compared with 30,000 X5s. Infiniti, on the other hand, hopes to sell 20,000 FXs annually.

The X6, although based on the X5 SAV (BMW-speak for "sports activity vehicle"), isn't an SUV at all. Nope, BMW says it's an SAC - a "sports activity coupe" - a new type of vehicle that's designed to appeal to buyers who would want a 6-series, had they not gotten used to their SUV's high seating position. So the SAC is the post-SUV SAV, if you catch their drift. We did - kind of - but still don't get the AMC Eagle styling and the fender gaps big enough for another set of wheels. The X6 would look a lot better with a three-inch lowering kit - but then BMW would have to concoct some other three-letter acronym to describe it.

SUV, SAC, or whatever, the X6 measures within an inch or two of the FX in every key dimension, inside and out. The X6 shares its wheelbase with the seven-passenger X5 but is about an inch longer, two inches wider, and three inches lower. Its radically sloping roof gives the impression that the rear seats are uninhabitable - but that's not the case at all. In fact, rear headroom suffers by only 1.2 inches compared with the X5, and the X6's rear seats are quite comfortable. You won't mistake legroom for that of a long-wheelbase 7-series, but four adults wouldn't be uncomfortable taking a long trip in the X6. Their luggage would fit, too - the X6 actually has more cargo space than the X5 (and even the FX) with the seats up. Of course, the sloping rear hatch means that tall items - like a washing machine - won't fit as easily. That's what rental trucks are for.

Up front, the X6 shares its basic dash layout, as well as its comfortable driving position and clear, easy-to-read instruments, with the X5. The controls are modern BMW, which means that the steering wheel is delightfully thick and offers excellent steering feel. The dreaded iDrive controller now has lost its ability to give force-feedback, making it even less intuitive than before. However, our test vehicle's optional leather-covered dashboard was beautifully upholstered, and the contrasting light-colored seats gave extra flair to what is otherwise a very all-business cabin. We highly recommend the optional rearview camera, since the X6's mail-slot rear window could obscure the large building you're about to back into.

Under the hood is an all-new, 4.4-liter twin-turbo V-8 that produces 400 hp and 450 lb-ft of torque. BMW says that locating the turbochargers in the valley of the engine block (see Techtonics) helps reduce lag, but unfortunately, the V-8's throttle response is anything but linear. Off the line, moderate pedal inputs are met with lazy nothingness, followed by way more power than you thought you asked for. The new engine may be a packaging marvel and may have a broad torque plateau, but to the driving enthusiast, it's no match for Infiniti's normally aspirated music box.

The X6's blistering acceleration, however, leaves nothing to complain about. It's slightly faster than the FX50, beating the Infiniti to the 60-mph and quarter-mile markers by 0.3 second. With 10 additional hp and 81 more lb-ft of torque, we expected the BMW to be even quicker - until we learned its weight. At 5270 pounds, even the strongest Toontown passenger-car scales explode - sending springs and dials flying in every direction - at the mere suggestion of weighing an X6. The FX50, a heavyweight itself, is 722 pounds lighter.

The X6's ride is even more supple than the FX50's, thanks to active antiroll bars and BMW's EDC system (computer-controlled dampers similar to those in the Infiniti). But whereas the remainder of Infiniti's techno tricks are gizmo driver aids, the BMW has one last go-fast rabbit to pull out of its hat: Dynamic Performance Control.

DPC is a new active rear differential that can shuffle engine torque (or engine drag) between the two rear wheels. Similar in concept to other torque-vectoring systems, DPC works in concert with the X6's xDrive all-wheel-drive hardware to apportion engine torque to the wheel or wheels that can best deal with it.

DPC works at all speeds, not just during insane cornering, and it helps steer the car using the rear wheels even in normal driving. As a result, the X6 feels hundreds of pounds lighter on its feet than an X5. The biggest breakthrough of DPC, however, is how it interfaces with DSC (stability control). Rather than cutting power and applying brakes to steer the car, the combined systems first try to correct the X6's path using torque vectoring. The result is that the vehicle simply turns smoothly, without the sometimes violent brake interventions and frustrating power reduction we've come to expect when the stability control light is flashing.

The X6's performance on a racetrack is downright shocking. BMW says that it will lap the Nürburgring in just over eight and a half minutes - only a few seconds slower than the last M3. That kind of performance is, thankfully, irrelevant to the X6's intended audience - frankly, the idea of empty-nesters drifting a 5300-pound SUV at Porsche 911 speeds on public roads is downright horrifying.

If the X6's buyers don't take it to the track, then it's left to win buyers on its looks alone. And that doesn't bode well. The FX50 makes more sense to us - with nearly identical performance, five-passenger seating, and a lower price, it clearly will appeal to more buyers. With brakes similar to those on the 900-pound-lighter G37, though, it experiences significant brake fade.

That's but one example of the inevitable. Both of these tall, corpulent trucks look - and perform - like they're from Toontown, but they'll be driven on earth, where the laws of physics apply. With a little electronic sorcery, each vehicle dupes its driver into thinking he's behind the wheel of a sport sedan. But that's an illusion; a cartoon, if you will.

Remember what your mom always said - don't try to do what they do in the cartoons, or you might get hurt.

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