For most people, purchasing a large luxury coupe or convertible is entirely an act of passion and indulgence, and right or wrong, outward appearance can make or break the deal. Compared to the sleek offerings from rival manufacturers Mercedes-Benz and Jaguar, well…let's just say the 2008 BMW 6 Series has a great personality. If there is such a thing as a sleeper among the entries in the big-ticket touring class, this is it. Only when you've taken the time to become fully acquainted with its pure driving dynamics, innovative use of technology and lower price of entry does the 6 Series' true beauty become apparent.

In its fifth year of production, the rear-wheel-drive, four-passenger BMW 650i coupe is based on the same platform used for the 5 Series sedan. But BMW aims the 6 Series higher. It has but one engine available, a 4.8-liter V8. Not a single body panel is shared with the sedan, and the front and rear suspensions are likewise calibrated for the 650's lower ride height and sportier intentions. To keep its weight in check, aluminum is used extensively for the suspension, hood and doors. Thermoplastic front fenders and a composite deck lid do their high-tech best to keep the 6 Series feeling spry, though this is still essentially a 4,000-pound car.

BMW equips its 6 Series well in terms of equipment, and you'll find but a handful of features that are optional. Convertibles use a fully lined folding soft top rather than a retractable hardtop, but it's a sophisticated design capable of keeping interior noise to sedanlike levels. The glass rear window opens for ventilation when the roof is up, and can be raised to act as a wind buffer when the top is down. If you don't want to go the convertible route, the 6 Series coupe feels nearly as airy, thanks to its large glass roof section. The glass is too large to slide open, but you can tilt it up slightly for ventilation.

Among high-dollar touring coupes and convertibles, the 2008 BMW 6 Series is easily one of our top recommendations. However, for buyers chiefly interested in style and opulence, the sleeker Mercedes-Benz CL550 and Jaguar XK/XKR will prove more satisfying. The same goes for the highly regarded Mercedes SL550 roadster. For enthusiast types who care about the drive above all else, the smaller Porsche 911 is likely the better choice, as it easily outhandles this plus-size Bimmer coupe.

Yet these cars are all more expensive than the 6 Series. And while cost concerns are seldom of primary concern in this segment, when a car strikes that near-perfect compromise between coddling its passengers and thrilling its driver that the 2008 BMW 650i does, such a value proposition is hard to ignore.

Available in both coupe and convertible body styles, the 2008 BMW 650i comes with a healthy complement of standard features including 18-inch wheels, adaptive xenon headlights, leather upholstery, 12-way power front seats with driver memory, dual-zone automatic climate control, Bluetooth and an eight-speaker CD audio system with iPod integration and a regular auxiliary audio jack. The convertible has a power soft top with a power retractable rear window.

Two distinct option packages are available: Sport, which brings 19-inch alloy wheels, enhanced exterior trim and sport seats to the table; and Cold Weather, with heated seats and steering wheel. Other options include active steering, adaptive cruise control, upgraded leather upholstery, a surround-sound audio system, HD and satellite radios, a head-up display and keyless ignition/entry.

Motivation for both the rear-wheel-drive 650i coupe and convertible is provided by a 4.8-liter V8 rated at 360 horsepower and 360 pound-feet of torque. Shifting duties are carried out by either a six-speed manual or BMW's new six-speed automatic transmission with steering-wheel-mounted paddle shifters and downshift rev-matching.

Standard equipment includes front seat-mounted airbags, front knee airbags, active front head restraints and full-length side curtain airbags (coupe only). Also standard are antilock disc brakes, stability control and a subscription to BMW Assist emergency telematics. Convertibles come with a rollover protection system. Optional safety features include a night vision system that uses a thermal imaging camera to spot potential obstacles in the road up to 1,000 feet ahead, and a new lane departure warning system.

For a vehicle so laden with technological comfort and safety features, the 6 Series maintains a remarkably direct and visceral driving experience. Although not as nimble as the smaller 3 Series coupe, the 2008 BMW 650i is a very capable performer when driven hard. The Active Roll Stabilization system keeps the big coupe flat around corners, and the lightweight suspension does its part to maintain traction and soak up the bumps without diluting the lines of communication. Regardless of transmission choice, you're sure to enjoy the 650i's 4.8-liter V8. Like every BMW engine we've ever experienced, this V8 is silken and anxious to rev. Although there's a nice surge of power toward the top of the tachometer, there's plenty of torque available at any rpm.

Although elegant, the 2008 BMW 6 Series cockpit has a somewhat austere feel compared to its competitors. Still, everything's set up perfectly for driving, with BMW's familiar orange-lit analog gauges dead ahead, a thick steering wheel grip and supportive seating. BMW's iDrive control system reduces button clutter to a minimum, making for a clean dash design but confusing operation of many controls, even with the addition of this year's "shortcut" buttons.

Thanks to its generous dimensions and a panoramic glass roof in the coupe, the 650i feels spacious for two, but four adults make for a tight fit. Both cars have an easy-entry feature to ease access into the backseat, but only the convertible's is power-operated. Trunk space measures 13 cubic feet in the coupe and a still healthy 12.4 in the 650i convertible (10.6 when the top is down), and both cars have a pass-through to accommodate longer items.