- Sam Moses
- Price As Tested:
“All-new, now with a V8, faster and better than ever.”
There are so many sophisticated driving features that we could use five times our space for Driving Impressions merely describing them. What we want to say is that we had one of the most fantastic road-testing afternoons of our life, behind the wheel of our M6 convertible on a forgotten central California two-lane, particularly over one winding mountainous 51.3-mile leg during which we drove the topless M6 like we stole it, from a waystop with great food called Sagebrush Annie's to the Full of Beans coffee stop east of Ojai. It was such a desolate day that even at rocket speeds, we passed only one car, and only saw a couple coming the other direction. Rare air, where an M6 convertible works.
So there's your bottom line: if you want to fully enjoy the M6, you have to break the law. Uber-performance is not simply what it does best, it's the only thing it does better than, say, a plain BMW 640i. BMW press materials speak the precise truth when they say that "its exceptional dynamic potential is geared squarely towards the demands of track use." But even for track days, the M6 is so staggeringly fast that only the very best drivers can reach its exceptional dynamic potential.
Depending on who's doing the testing, the M6 will accelerate from 0 to 60 in 3.9 to 4.2 seconds, using the launch control that electronically prevents burnouts. Top speed is electronically limited to 155 mph, achievable by the M6 on a number of tracks around the country.
The new 4.4-liter twin turbo V8 engine is more compact than the V10 it replaces, and makes a bit more horsepower (560 hp) and torque (500 foot-pounds), while getting better fuel mileage. The engine, which redlines at 7200 rpm, is based on the V8 used in the X5 M and X6 M. There have been many changes to this V8, including increasing turbo boost pressure from 17.4 psi to 21.7 psi.
Some technical details. The two twin-scroll turbochargers are mounted in the V-space between the cylinder banks (along with catalytic converters). It's called a "reverse flow" engine because the intake ports face outward and exhaust ports inward, allowing shorter (and wider) intake runners and exhaust tracts, for less pressure loss and better heat management. There's a special 8-into-4 exhaust manifold feeding the four scrolls in the two turbochargers, a system that sharpens throttle response and reduces turbo lag to virtually zero.
Two exhaust pipes feed into one muffler that sprouts four tailpipes out through the rear diffuser. The resulting exhaust note via this unique path from the engine block is distinctive, although we must say not classically satisfying, like, say, a good old Mustang or a primitive pushrod 6.2-liter V8 Cadillac CTS-V. In fact, when we were treated to another M6 passing us at full throttle, we must say it sounded a bit junkyard dog-like. How dare us.
BMW calls its direct fuel injection High Precision, with capital letters, achtung. It's also high pressure, spraying fuel into the combustion chambers at nearly 3000 psi. The new engine also uses BMW's VALVETRONIC variable valve control, which controls power by varying the lift of the intake valves. The valve timing is also infinitely variable, with BMW's VANOS system controlling the camshafts, key to the remarkable broad torque, with all 500 foot-pounds available from 1500 to 5700 rpm. On the highway, the torque range is staggering.
Then there's the Auto Stop/Start feature, which saves some small amount of gas by turning the engine off every time the car stops moving, and turning it back on when you take your foot off the brake pedal. We'll limit our own comments to calling it annoying, being jerky and audible; and we'll add that it doesn't avoid the $1300 gas-guzzler tax. We're skeptical about how much fuel it saves and are inclined to switch it off. Auto Stop/Start can be de-activated, though the 300-page owner's manual is totally unclear about this. Our thinking is that you have to press the Auto Off button every time you start the car to keep the engine from shutting off at intersections. It's the same story in the new 3 Series.
Unlike other 6 Series BMWs, which use a button to select up to five driving modes, the M6 has three settings each for the shock absorber stiffness and damping, transmission shifting, throttle response, steering quickness and weight, and stability control (that's 243 options, if our math is correct). And then, on the steering wheel, there are M1 and M2 buttons, which basically mean Memory, for two of those programs.
Given this, there's nothing we can say, because whenever we comment on how something feels, there are 242 chances for us to be wrong. If the ride is too firm for you, find a softer setting. If the steering is too slow, make it quicker. And so on.
You can't change the brakes, which are quite sensitive, nicely so; and humongously potent, as they should be, for this 155-mph car that weighs 4500 pounds (convertible). You can, however, spend a lot of money and get ceramic brake rotors, for the track. On the road they might look cool, especially through the thin spokes of the optional 20-inch wheels, but they're not practical because they need to be hot to work their best.
BMW estimates the fuel mileage at 14 mpg in the city, 20 mpg on the highway, or 16 mpg combined. We got 13.6 mpg. We hammered it a lot.
Speaking of hammering it, if you don't have the Head-up Display with a shift light, just short-shift when you're accelerating hard, because it's so fast you don't want to take your eyes off the road to read the tach. And because there's so much torque over such a broad range, it almost doesn't matter which gear you're in.
The transmission is a high-tech high-torque 7-speed double clutch, with paddle shifters. With all the different modes, it will do anything you want it to do, including behave like a sophisticated racecar transmission, or like a docile street automatic. It's linked to a new active differential that optimizes power transfer between the rear wheels.