M Stands For All-Wheel Drive
We appear to be in a serious situation here. Scientists tell us carbon emissions have hijacked the atmosphere and that global temperatures are going up. Raging storms assault unprepared coastal locales with alarming ferocity. The American Midwest remains frozen solid even as the polar ice caps melt and the seas rise.
The reason for this calamity? Apparently someone's been having a little too much fun driving. Gone, some say, are the days of the 500-hp V8; from here on out, the EPA will relegate us all to driving 80-hp electric shitboxes so that the flowers may again bloom in spring.
BMW obviously didn't get the memo. The company's high performance division has just released two new M cars, each equipped with a 550-hp turbocharged V8. And both of them are SUVs. (Or, in BMW-speak, SAVs.) Put that in your pipe, Sacramento.
The X5 M at least has been a long time coming, the platform having existed since 1999. And technically speaking, both of these vehicles are virtually identical by the numbers. The X6 M differs in that it deletes a passenger seat at the rear, is almost an inch longer and nearly half an inch narrower, and gives up about 3 inches of height due to the swooping "coupe profile." Everything else is identical-front and rear track, wheelbase, power output and performance, even weight.
Standard equipment is the same too. Topping the list is the M powerplant, in this case the new twin-turbo V8. This engine concept isn't all new, having been introduced last year in the original X6 and the latest 7 Series. This version, though, called the M TwinPower Turbo, has been through the M Technik wringer. And that of course means even more power. It employs what's called Twin Scroll Twin Turbo Technology, along with a joint exhaust manifold serving both rows of cylinders, enabled by placing the turbochargers and catalysts inside the cylinder bank vee. It serves to shorten the length of the pipes and manifolds and increase their cross section to increase the forced induction system's efficiency.
Max power is 408 kW-555 DIN hp, or 547 in SAE terms. More impressive is the torque curve, which really is more of a plateau: 501 lb-ft delivered on a peak ranging from 1500 to 5650 rpm. And all joking aside, it isn't as grossly inefficient as it might sound, meeting the EU5 emission standards and returning a combined economy average equivalent to about 20 mpg.
Besides being the first turbocharged M cars, these models mark a number of other firsts. They are the first M models with all-wheel drive, as well as the first to be equipped with a true automatic transmission. Called the M Sports Automatic, it offers three shift modes: D, S, and M, the latter requiring you to row through the gears yourself. In full manual mode it uses a torque-reducing function wherein individual cylinders are switched off by canceling out the fuel injection and ignition in order to achieve shorter, more satisfying gearshift times. Gear selection comes by way of the central gear lever or steering wheel paddles sculpted from aluminum.
M mode also allows access to the Launch Control function, activated by pressing the brake pedal and pushing the throttle past 60 percent, which places the system in standby. Once the brakes are released, the SAV accelerates with full power; in the process, the transmission automatically shifts gears at optimized points within the rev range, with the fastest possible shift times and optimum slip control.
The dynamic portion of our test drive took place at the Road Atlanta raceway. Slinging this beast around those high-speed bends, I quickly gave up on full manual gear selection. As with most modern "smart" trannies, the automatic's sporting S mode gives an almost clairvoyant insight into your driving mindset; in this case, it facilitates maximum performance while allowing more concentration on following your line than on flailing for gear levers or slapping at aluminum paddles cranked at unaccommodating angles.
Power goes to the ground through BMW's proprietary four-wheel xDrive system. In this case, xDrive uses what they call optimum dynamics; essentially, it's been set up for a greater power bias toward the rear. But the variable power distribution remains programmed to read driving conditions and direct power fore or aft, even before wheels start to slip, in order to preclude both under- and oversteer and pre-empt stability control interference.
With such prodigious levels of power, mass, and grip, it's frightening to imagine things going horribly out of shape. An out-of-control X6 M would seem to constitute an astounding release of energy, something on the order of splitting atoms. That's where you come to appreciate the inherent safety and driver-aid systems: DSC stability electronics, the M-tuned air suspension, Adaptive Drive with electronically adjustable dampers (EDC), and active anti-roll.
And in case you like to tempt fate, M Dynamic Mode (activated by the DSC button) raises the intervention thresholds of the aforementioned systems. Your inner hoodlum will likely approve.
Did the world need a 550-hp SUV, much less two of them? Probably not, but the idea remains a compelling one. And in spite of this apocalyptic age, these are two of the most powerful yet. Priced just south of $90,000, they look to be wholly competitive in the ML63/Cayenne Turbo landscape. Whether or not the market will continue to embrace such vehicles is another question. But in terms of sheer audacity, each must receive our seal of approval.
2010 BMW X6 M
Longitudinal front engine, all-wheel drive
4.2-liter V8, dohc, 32-valve, turbocharged and intercooled
Double-wishbone/multi-link front, Integral IV (four-link) rear, BMW M-specific elastokinematics and springs
Four-piston fixed calipers, 15.6-inch rotors (f), single-piston floating calipers, 15.2-inch rotors (r)
Length/Width/Height (in.): 192.0/78.1/66.3
Wheelbase: 115.5 in.
Curb Weight: 5,326 lb
Peak Power: 547 hp @ 6000 rpm
Peak Torque: 500 lb-ft @ 1500 rpm
0-60 mph: 4.5 sec.
Top Speed: 155 mph (limited)