Now in its third generation, the BMW 6 Series occupies a special niche in the automaker's lineup. It's alternately been the company's flagship GT platform and an experimental canvas, the latter for former design chief Chris Bangle's polarizing exteriors.

With this year's full redesign, the 2012 BMW 6 Series largely shakes off the Bangle legacy looking a little longer, wider, shorter and sharper. The larger dimensions are attributed to a new aluminum-intensive rear-wheel-drive architecture that BMW says is 50 percent stiffer than its predecessor.

And the chassis needs that extra rigidity given the engines underhood. The old V8 wasn't exactly a slouch, but its acceleration is now matched by the more fuel-efficient turbocharged six-cylinder found in the new 640i model. For those wanting even more, the new V8 in the 650i will definitely get the job done. Slightly smaller than its predecessor, the twin-turbo 4.4-liter makes more horsepower and nearly 100 pound-feet more low-end torque. It makes for a 650i that accelerates to 60 mph just a few tenths shy of the former V10-powered M6.

Inside, the 6 Series has a beautifully sculpted cabin with a more driver-focused dashboard than that of the old model. Along with the new 10.2-inch navigation display, it's clearly evident through the attention to detail lavished on the instruments, controls and overall design that BMW has taken a good deal more time developing the interior than it did with its predecessor. As for the convertible, it continues to feature the clever rear window that's separate from the folding top and can be lowered to allow the breeze in while still keeping the sun off.

Taken all together, the 2012 BMW 6 Series shapes up to be a very impressive grand touring coupe and convertible. There are a couple of competing models to also consider, of course. With classic curves and a lightweight aluminum structure, the Jaguar XK is a competitor with character and performance in equal measures, while the Mercedes-Benz E550 offers comparable luxury for less, plus actual room for rear seat passengers. But imbued with new style and strength, the 6 Series is one of the most exhilarating luxury experiences you can have behind the wheel.

The 2012 BMW 6 Series is available in 640i and 650i trim levels, both of which can be had as a coupe or a convertible.

Standard equipment on the 640i includes 18-inch wheels, an adaptive suspension, automatic and adaptive xenon headlights, LED foglights, automatic wipers, parking sensors, power-folding mirrors, a large tilt-only sunroof, keyless ignition/entry, 10-way power front seats with four-way lumbar adjustments and memory functions, leather upholstery, a power tilt-and-telescoping steering wheel, auto-dimming mirrors, dual-zone automatic climate control, cruise control and a rearview camera. Electronic features include Bluetooth, a nine-speaker sound system (with a CD player, HD radio and an auxiliary audio jack), a navigation system, voice controls and the iDrive electronics interface. The convertible has a power soft top with a glass rear window that can be raised and lowered independently, along with heat-reflective leather upholstery.

The 650i differs with a V8 engine, 19-inch alloy wheels and 16-way comfort seats. The latter two items are available on the 640i.

Options include the Driver Assistance Package that adds side- and top-view cameras, blind spot detection, a head-up display, lane departure warning and automatic high beams. The Luxury Seating package adds a power rear sunshade and ventilated front seat with adjustable bolsters and a massage feature. The Cold Weather package mixes it up with heated front seats (also available as a stand-alone option), a heated steering wheel and a trunk pass-through ski bag. The Premium Sound package adds a 16-speaker Bang & Olufsen sound system with an iPod/USB audio interface and satellite radio.

Other options include 20-inch wheels, LED headlights, active steering, active roll stabilization, an infrared night vision display, BMW Apps enhanced smartphone integration, extended leather upholstery and enhanced interior trim materials.

The 2012 BMW 640i is powered by a 3.0-liter turbocharged inline-6 that produces 315 horsepower and 332 lb-ft of torque. Rear-wheel drive and an eight-speed automatic transmission are standard, along with an automatic start/stop system that shuts down the engine when stopped to save fuel. BMW estimates that the 640i will go from zero to 60 mph in 5.5 seconds -- quicker than the old V8-powered 6 Series.

The 2012 BMW 650i is powered by a 4.4-liter twin-turbo V8 generating 400 hp and 450 lb-ft of torque. Rear-wheel drive is standard, but "xDrive" all-wheel drive is optional. An eight-speed automatic transmission with manual shift control is standard, and a six-speed manual is optional on rear-drive cars. The start/stop feature is not included. In Edmunds performance testing, a manual-equipped 650i coupe went from zero to 60 mph in 5.2 seconds. Interestingly, we timed a heavier automatic-equipped 650i convertible from zero to 60 mph in a quicker 4.9 seconds. EPA-estimated fuel economy for an automatic-equipped convertible stands at 16 mpg city/24 mpg highway and 19 mpg combined. Opting for the manual drops those to 15/22/17.

Standard safety equipment includes four-wheel antilock brakes with advanced standby and drying features, traction and stability control, front-seat side airbags, front knee airbags, active head restraints and BMW Assist. Pop-up roll bars also come standard on the convertible. In Edmunds brake testing, the 650i coupe stopped from 60 mph in 109 feet. The convertible was virtually identical -- impressive stops for cars that tip the scales at 4,200 pounds.

Behind the wheel, no one will mistake the 2012 BMW 6 Series for a 3 Series. The 6 makes few sporting pretensions, and while we wouldn't call it athletic, it's also not at all wayward or uncoordinated. The optional Active Roll Stabilization system keeps the brawny coupe composed through corners and helps it change direction quicker than its 2-ton heft would suggest. The steering changes weight depending on the driver-selected dynamic mode (such as Normal or Sport), but in all forms, it remains reasonably precise. Optional Active Steering also uses rear-wheel steering for low-speed maneuverability and high-speed stability.

Where the 650i's previous engine made its best power near its redline, the new twin-turbo V8 unleashes a seemingly endless flow of low-end grunt and properly competes with torque-rich engines in the Jaguar XK and Mercedes-Benz E550. The new 640i also performs quite well, however, and it's definitely worth a drive to see if you really need that higher-numbered model.

It's not as elegant as the Jaguar XK's streamlined design, but the 2012 BMW 6 Series interior offers top-shelf materials and craftsmanship in a fitting, cockpit-centric design. Depending on your preference, the center console's high hip line may instill a sense of security or slight claustrophobia. Improvements to successive generations of iDrive make it one of the most intuitive interfaces for controlling phone, navigation and audio functions. The latest upgrade, featuring a 10.2-inch color display, makes cycling through essential menus even easier.

The 6 Series excels at accommodating two passengers, but the rear seat is only suitable for adults on short trips to the restaurant or driving range. Trunk space measures a relatively enormous 12.3 cubic feet in the convertible (10.6 with the top down) and both cars have a pass-through to accommodate longer items. The convertible's heated rear window retracts independently of the soft top, doubling as a wind deflector when the top is dropped. Lowering the soft top takes about 20 seconds; raising it takes just a few seconds longer.