Sabtu, 25 Juni 2011

BMW X6 xDrive50i

BMW X6 xDrive50i
I must be missing the gene that makes high-riding vehicles appealing to so many other people. As a car enthusiast and an engineer, I can certainly appreciate the performance that companies like BMW and Infiniti have managed to wrangle from vehicles like the X6 and the EX35. But there is absolutely nothing in the new 2009 BMW X6 that couldn't be done better in a vehicle with a normal car-like ride height. After all, who is going off-roading in one of these? The best explanation I could get out of BMW officials for the existence of the X6 is that many drivers like that commanding view of their surroundings that the elevated altitude provides.
According to BMW, the X6 is designed to provide stylish coupe looks with the high performance people expect of a BMW and the utility of an SUV. As is so often the case, vehicles that try to fit too many categories at once end up not fitting any of them very well. It's not all bad news for the new X6, though. While it's not my cup of tea, there are undoubtedly some who will love this beast. Read on after the jump to find out if the X6 is something you might want in your garage.
The brand from Munich is hosting the world's automotive press in several waves this week at its U.S. manufacturing base in Spartanburg, South Carolina. The purpose of this gathering is the driving launch of this latest product for a niche no one knew existed. BMW calls the X6 a Sport Activity Coupe, and given that the market seems to be accepting the idea of four-door coupes, that part is at least plausible. In the light of day, the X6 actually appears more visually appealing than it did under the auto show lights at Cobo Hall in January when we first saw the production version. BMW actually started building the X6 the same week it debuted in January and has now completed the ramp up to full production.
The basic shape of the X6 catches your eye with its sloping roof-line and a surface that captures light at various angles. The creases in that surface provide visual interest without looking like the clash of ideas that some of the earlier Bangle-era BMWs had. There are none of the odd cut-lines or seemingly randomly tacked on visual elements like the trunk of the current 7-series. The tall stance afforded by the big wheels gives the appearance of a vehicle that could enter the Dakar rally. With the luxury interior gutted and some sand tires, the X6 would look right at home racing across the Sahara, much like the Porsche 959 did in the late '80s.
However, we did not come to South Carolina to drive the X6 in the desert. Instead, we paired off and BMW provided each of us with keys to either an X6 xDrive35i or X6 xDrive50i. By the way, we talked to BMW about that new nomenclature and how clumsy it is. Although they acknowledge that the names are longer than might be desirable, they wanted the name to reflect the powertrain combination and fully expect people to refer to their cars as X5, X6 etc. But I digress. Lou Ann Hammond from Carlist.com and I set off in a white 35i on a 150-mile route set up by BMW to let us evaluate the X6 in a variety of conditions.

The test route meandered northwest from Greenville, South Carolina up into the mountains through Caesar's Head State Park and on to Brevard, North Carolina. Along the way we passed through Table Rock State Park. In the mountains we encountered plenty of serpentine pavement where we were able to thoroughly exercise the sporting pretensions of the X6. The 35i we had was propelled by the same twin turbo 3.0L inline-six that has provided such fine service in recent 3- and 5-Series models. Neither of those cars, however, have to haul around quite as much mass as the X6. The 35i weighs in at 4,728 lbs. empty.

BMW claims a 0-60 time of 6.7 seconds from the 306-hp, 295 lb-ft six-cylinder. While that is certainly plausible on level ground, accelerating uphill out of a tight turn has the engine feeling like it's working pretty hard. It never really felt slow, but it certainly didn't feel relaxed. The X6 has a pretty sophisticated drivetrain with a torque vectoring xDrive system that sends power not only to the corners that have grip, but can also redirect it to help the vehicle turn in on corners. Electronically controlled clutches on either side of the rear differential assign the torque much like Acura's Super Handling-All Wheel Drive. Unlike the Acura system that disengages under braking, the BMW set up works all the time.

Adaptive damping and anti-roll control help keep the X6 relatively parallel to the ground even under hard cornering. However, even the most sophisticated chassis hardware can't change the laws of physics. The X6 is a two and a half ton vehicle, the antithesis of everything the late Colin Chapman stood for. He would have been appalled at the thought of calling something so heavy a sport vehicle. For something this porky, however, it was amazingly nimble.

One driver on our ride did manage to find the limits, though, as a cold fog descended on the mountain region we were driving through. As the temperature dipped into the low 30s, he approached a corner a little too hot and slid off the road. Fortunately, the only injury was too the X6, but it served as a reminder that physics will always win. Nonetheless, the six-cylinder X6 proved to be reasonably well balanced even if you could feel all of that weight.
From Brevard we turned back south eventually ending up in Laurens, South Carolina, home to Michelin's U.S. proving ground. At the track we got to swap for a 50i powered by BMW's new 4.4L twin-turbo V8. This new engine is unusually compact thanks to packaging that stuffs the two turbochargers into the valley between the banks. Direct injection puts the premium gas straight into the combustion chamber, and the engine is able to use a 10:1 compression ratio without worries of pre-ignition. The bottom line is 407 hp and 442 lb-ft of torque.

Unfortunately, the extra ability to increase velocity also comes with an extra 300 lbs, most of which sits over the front axle. At the Michelin facility, there were both wet and dry tracks set up that included slalom and double lane change sections. On those agility tests, the X6 was surprisingly adept, changing direction and avoiding obstacles easily. However, when pushed hard on the track, the V8-powered X6 understeered more than the the six-cylinder version as the condition of the tires attests (see below). The front tires showed substantial shoulder wear while the rears had much more even wear.

So what does all this mean? There are undoubtedly some out there who will like the combination of this coupe-like body style and SUV ride height. Almost certainly no one who actually chooses to buy an X6 will drive it with anywhere near the aggression we did this week. Personally I wouldn't mind seeing something like this body sitting on a 5-Series chassis lower to the ground and with about 1,500 lbs less mass.

What about the supposed utility of the X6? The cargo area behind the seats holds 20.1 cu.ft of stuff. Folding down the back seats increases that to 51 cu.ft. Yes, that back seat. Upon seeing the sloping back light, there were obvious concerns about space for passengers back there. Leg room is no problem, but head room depends largely on the body proportions of the passengers. One attendee who had several inches of height on my 5'10" stature had no problem with head room. Those with a longer torso like myself will find their head hitting the roof. That downward sloping roof-line combined with a relatively high trailing edge to the lid also means the rear glass is little more than a horizontal slit. Fortunately, most American drivers don't seem to look at what's coming up behind them anyway, so that shouldn't really pose a problem for them. Otherwise, outward visibility is fine.
The driver's environment is pretty standard fare for current BMWs, including the oft-maligned i-Drive interface. The six-speed automatic also includes paddle shifters on the steering wheel. One interior design element that BMW made a point of mentioning is the ability for the cup holders to hold two 44-ounce drinks, which means the X6 will certainly be welcome at 7-Eleven. With the X6 now in full production at the Spartanburg plant, BMW is declining to say how many they hope to sell. They did indicate that exports will should account for about half of production, with Europe, the Middle East and Russia as the primary markets. Lou Ann and I agreed that BMW should help the U.S. trade deficit and export them all. Or at least make them into Dakar rally specials.

The BMW X6 is a mid-size luxury crossover released for sale in the second quarter of 2008 by German automaker BMW. The X6 was marketed as a Sports Activity Coupé (SAC) by BMW. It combines the attributes of an SUV (high ground clearance, all wheel drive and all-weather ability, large wheels and tires) with the stance of a coupé (bold styling, dramatic sloping roof).

As the photos show, the X6 is anything but a conservative design.
The X6's roofline begins arching downward after the B-pillar and continues plunging right to the X6's rising waistline. As a result, second-row headroom and rear cargo volume are both compromised.



 The new X6 is longer and lower than the new X5, seating only four. But what the sporty X6 loses in seating and storage, it gains in performance.
Compared to the X5, the X6 has almost an inch of additional wheelbase length, and two inches of added width. The overall height of the X6 is a whopping 3.3 inches lower than that of the X5.

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