Rating: 8.4
Bottom Line:
The M6 convertible’s thunderous new twin-turbocharged 560-horsepower V8 engine makes it a performance standout, and its occupants are coddled by a richly equipped and exquisitely finished interior, but it takes all of the Motorsport division’s savvy and tricks to make this 2-ton grand touring car handle.
  • Enthralling performance
  • Excellent fit and finish
  • Elegant looks
  • Heavier than its predecessor
  • Useless rear seats
  • Limited visibility and trunk volume

BMW is constantly expanding and renewing the model portfolio of its Motorsport GmbH performance division, its creations best known by their simple "M" prefix. The latest in this vaunted collection is a third-generation M6 derived from the recently redesigned 6-Series. First out of the blocks was the M6 convertible, which was then joined by the M6 coupe. An all-new 4-door M6 Gran Coupe will follow as a 2014 model. All three are powered by the same twin-turbo 4.4-liter V8 engine as the newest M5 super sedan. This 560-horsepower engine makes them the sportiest 6-Series variants ever, with style and luxury to match. The unfortunate price for these improvements is weight gain, running against the current trend for lighter vehicles in the high-end luxury and performance segments.

Model lineup
The M6 convertible is offered as a single model, with a healthy number of available interior trim and color variations. The car is easily recognized by the black vertical slats of its twin-kidney grille, small M6 badge in the upper right corner, and its huge air intakes with matte-black honeycomb grille inserts. The flared front and rear fenders that stretch over the M6's bigger tires are molded thermoplastic. The front fenders feature chromed M-series gills set in the upper corner of the deltas where the sculpted character lines converge. While the hood and doors are made of aluminum, the trunk lid and roof compartment cover are made from glass-fiber-rich sheet-molding compound.

Its black, power soft-top opens in about 20 seconds and flips back up in a handful more at speeds up to 25 mph. It has a narrow, shallow, glass rear window — with defroster — that can be lowered independently according to your preferences in ventilation. With the sizable blind spots the top generates, the standard front and rear parking sensors are no luxury. BMW has thankfully equipped its potent new convertible with aluminum roll bars that will pop up if sensors detect a potential rollover.

The open-top M6 is richly equipped. Listed as standard features are an automatic engine start-stop mode, Efficient Dynamics brake-energy recuperation, adjustable suspension damping, heated multifunction front seats with adjustable lumbar support, keyless entry, a rearview camera, xenon headlights with adaptive light control, a navigation system with BMW Assist and Bluetooth connectivity, tire pressure monitoring, anti-theft alarm, a ski bag and carbon-fiber trim.

The Driver Assistance package ($1,900) includes automatic high-beam dimming, lane-departure and blind-spot detection systems and parking cameras. The infrared-based Night Vision system, aimed at maximizing pedestrian detection in all conditions, is an extra $2,600. To all this, the Executive package ($4,900) adds a heated steering wheel, soft-close automatic doors, active front seats, full LED lights, BMW's multicolor head-up display, satellite radio and BMW Apps.

To indulge entirely, full Merino leather trim is $3,500, two-tone Merino leather adds $5,000, while the Bang & Olufsen audio system goes for $3,700.

Under the hood
The 4.4-liter V8 engine features a pair of twin-scroll turbochargers mounted between the engine's cylinder banks along with the exhaust catalysts. This innovative "reverse-flow" concept minimizes turbo lag, sharpens throttle response and reduces cold-start emissions. The V8 produces 560 horsepower at 5750 rpm and 500 lb-ft of torque at only 1500 rpm, making it the most powerful engine ever mounted in a production BMW. All that grunt gets to the M6's chunky rear tires through a 7-speed dual-automated clutch gearbox only.

BMW says the new M6 convertible sprints from zero to 60 in 4.2 seconds. The slightly lighter M6 coupe takes 4.1 seconds, thanks to standard launch control. Yet fuel economy is reportedly improved by 23 percent over the previous model, thanks to the engine's new Valvetronic induction control, infinitely variable valve actuation, and other trickery such as brake energy regeneration and auto start-stop.

Inner space
In keeping with the M6 convertible's top rank on the Motorsport family tree, its cockpit is a generous blend of opulence and performance accoutrements. Basic instrument-panel design is shared with 5-, 6- and 7-Series relatives, but treatment and execution are definitively jazzier and richer. A thick-rimmed sport wheel and a dashboard and console that mix full leather and carbon-fiber trim set the tone, along with a wide aluminum-faced footrest.

New Motorsport seats are well-sculpted and draped with notably thick leather. They have multiple power adjustments that can be saved and recalled with memory settings that include lumbar support and the exterior mirror. A manually adjusted cushion also lets you tailor thigh support.

The instrument cluster, dead ahead for the driver, has a set of four classic round gauges with the large speedometer and tachometer taking center stage. A small screen between the larger gauges displays the gear engaged and your selection of additional vehicle info elements. Although improved, the iDrive system interface still has its challenges, but the center-mounted 10.2-inch screen's clear graphics mitigate the issue to some extent.

A neat feature is the pair of programmable M Drive buttons on the left spoke of the steering wheel. Each one lets the driver pick a combination of settings for the dual-clutch gearbox, the variable-ratio and speed-sensitive hydraulic power steering and the electronically adjustable shock absorbers. For these you get to choose between three modes: Comfort, Sport and Sport Plus. The M buttons let you call up your favorite mix of settings for these systems, as well as for BMW's Dynamic Stability Control and the various data screens available with the optional full-color head-up display.

On the road
The wizards in the Motorsport division had to use all the tricks they know to get the best possible comfort, handling and performance out of a car that weighs two-and-a-quarter tons. At 4,508 pounds, the new M6 convertible is 110 pounds heavier than the previous model, in spite of the lightweight materials used throughout the car. To deliver this weighty package, M6 creators first needed abundant grip and got it with 265/40R19 tires in front and 295/35R19 at the rear, kept in check by an electronically controlled limited-slip differential. The optional 20-inch light-alloy wheels get 265/35 ZR20 and 295/30 ZR20 rubber. Suspension subframes are also rigidly bolted to the body shell for greater precision.

Braking is strong, with standard 15.7 and 15.6-inch steel rotors installed front and rear. Both M6 models are the first M cars available with lightweight carbon-ceramic brakes that are fade-free. With larger 16.1-inch front rotors, 20-inch wheels are required. The rear discs are still 15.6 inches in diameter.

The M6 convertible is a smooth cruiser in Comfort mode, with an almost mushy throttle response. Things are quiet, top up, with only slight wind rustle at highway speeds. With the top folded and tucked away, wind buffeting is minimal if you keep all the glass up, rear window included. The ride is predictably firm, but the form-fitting seats keep things quite bearable in front. Forget the rear seats unless you are ready to give up an appreciable part of front seat room.

Its character does not morph from Jekyll to Hyde when you go from Comfort to Sport mode, but the changes are quite noticeable nonetheless. While things firm up nicely in Sport mode, Sport + mode is best left for track days or hard driving on truly deserted twisty roads. We did encounter a few twisties at the M6's launch in California. At full-tilt, even briefly, the M6 is enthralling.

Engine sound goes from a deep and unusually raucous growl at lower revs to a ferocious wail as you let the tach needle sweep to the 7200 rpm redline. With the steering-mounted paddles, upshifts are instantaneous in Sport + and keep you pinned to the seatback. The M6 simply devours corners at any speed with hefty steering effort and moderate feedback. You will need a track to touch its limits.

Right for you?
The M6 convertible was launched in June 2012 and is now available as a 2013 model with a starting price of $114,650, while its coupe sibling has a base price of $108,350. Sleek and muscular, it is a rare epicurean feast of luxury, style, handling and performance.

Tightly built and superbly crafted inside and out, the M6 will trigger sensory overload at the touch of a few buttons and pedals. You can only imagine how impressive it would be with a few hundred pounds less to carry around. As it stands, this new drop-top M6 is a feisty grand-touring convertible at best, not a sports car.

(As part of a sponsored press event, the automaker provided MSN with travel and accommodations to facilitate this report.)

A professional auto journalist for more than 25 years and the founding editor of Sympatico / MSN Autos, Marc Lachapelle is a two-time winner of the Canadian Journalist of the Year award from the Automobile Journalists Association of Canada, an accomplished photographer and licensed racer.