Dearest M5 Fans,
It's 11:41 pm and I've just returned from dinner with BMW executives after spending 125 miles behind the wheel of the new M5. I have nineteen minutes until my midnight deadline for this story, so what you're going to get is whatever I can type in the next couple of minutes.
First thing's first: the M5 uses a hydraulic steering rack. No fancy active steering, and no electric assist. What does that mean? Well, driving down the cobblestone driveway of our Spanish hotel, I let out a big "it's alliiiiiiiiive!" Steering feel, even at 10 mph, is alive and well in the M5 - which is in distinct contrast to the rest of the 5-series lineup. BMW, I don't care about the 0.001 mpg saved by switching to electric power assist: clearly, this is the right solution. Bring back hydraulic steering on all 5- and 7-series, please.
Better yet, the steering is adjustable to three levels of weight: Comfort, which feels like a normal M product, Sport which is slightly heavier than, say, an M3, and is just plain perfect, and Sport Plus, which makes the steering wheel feel like it's attached to a bowl of split pea soup. It's way too heavy, and I say this not because I'm a weakling, but because the effort is so high but the self-centering tendency isn't: let go of the wheel around a corner and the car keeps turning. It feels unnatural.
The suspension, too, is adjustable in three settings. Comfort is stiff but comfortable, Sport is slightly stiffer, and Sport Plus should only be used by trained chiropractors. It's actually not that bad (on the standard nineteen-inch wheels) but it does come across as unnecessarily harsh. Hey, if you like that kind of thing, go for it. I'm fine with Comfort -- it does everything it needs to without beating you up.
The third adjustment is throttle response, and there are also three modes. Pick which one you like.
The engine, code S63TU B44, is an evolution of the 4.4-liter V-8 S63B44 that debuted in the X5M and X6M. The biggest change, philosophically, is the addition of Valvetronic, which, you'll remember, is BMW's infinitely variable intake valve lift system that eliminates the need for a conventional throttle. This is especially interesting, since M's trademark was always to have individual throttle butterflies for each cylinder. As BMW's brilliant American PR team points out, having Valvetronic on the sixteen intake valves is like having sixteen throttles. Kinda true.
The V-8 also wears two turbos, like before, but revisions to the intake allow higher flow. That, combined inexplicably with higher boost pressure (1.8 bar instead of 1.5) result in no significant power boost: the M5's S53TU makes 560 hp and 500 lb-ft of torque. (Those are provisional numbers; final U.S. tuning hasn't been done yet.) That's five more horses than the non-Valvetronic motor. Or less than one percent more.
The only transmission for us to drive today was the European-specification seven-speed twin-clutch automated manual. An engineer did confirm that a conventional six-speed manual will be available for the U.S. market when the M5 goes on sale in the summer of 2012. It's an existing transmission that's been beefed up for the M5's gargantuan torque. The twin-clutch auto tranny is exclusive to the M5 and it's a good one. Shifts are immediate, and depending on which mode you're in (there are three each for automatic and manual), they're either silky smooth or outrageously harsh. Or in between.
Helping put that power to the ground is a new electronically controlled locking rear differential that can steplessly vary lockup between fully open and fully locked. Strangely, the X6 M's torque-vectoring differential didn't make it into this application. I'll try to find out why. But suffice it to say that you feel the diff in a number of ways: one, no inside wheelspin, ever. Two, you feel the rear of the car shuffling around looking for traction. I love that feeling.
(Uh oh, 9 minutes left.)
How's it drive? Well it goes like stink, that's for sure. It feels even faster than the factory's quoted 4.4-second 0-to-62-mph time, but that number is clearly very traction-limited. On Southern Spain's slippery roads, the M5 easily roasts its tires in first and second and third and sometimes fourth - and it sure feels like the engine computer doesn't even bother to allow full boost in first gear. It'd be pointless anyway. It's very, very fast.