The 2014 BMW 6 Series coupe and convertible are long, sweeping grand touring cars that push just about all of the right buttons. They're good-looking, seriously powerful and suitable for long, comfortable journeys or simply cruising down Main Street. As you would expect, the 6 Series is equipped with all the latest technological gadgets and modern touches to make it very livable as well.

BMW gives you a choice of engines for the 6 Series. The base turbocharged inline six-cylinder in the 640i might hint at a lack of power, but in actuality, this car is quick enough to keep up with quite a number of V8-powered cars on the road while returning excellent fuel economy. If you're committed to high performance, though, it's going to be hard to turn away from the BMW 650i and its 445-horsepower turbocharged V8 engine. To make the 2014 6 Series even more appealing, BMW now offers both engines with either rear- or all-wheel drive in both the coupe and convertible body styles.

Refinement defines the 6 Series' interior, which features a driver-focused dashboard, a large, crisp navigation display and excellent build quality and materials. The convertible distinguishes itself with a rear window that can raise and lower independently from the soft top, along with upholstery that's treated to remain cool even in direct sunlight. However, the swooping design and appealing exterior of the car does affect passenger space in the rear. Though largely the norm for this class of car, the rear seats are best used for extra cargo space.

Competitors to consider include the classically good-looking Jaguar XK , which is a satisfying grand tourer in its own right, as well as a true sports car like the Porsche 911,which is much more engaging to drive. The Mercedes-Benz E-Class Coupe offers comparable luxury for less money, along with actual room for rear seat passengers. Still, imbued with style and strength, the 2014 BMW 6 Series is a fine choice for a luxury coupe or convertible.

The 2014 BMW 6 Series is available in 640i and 650i trim levels. Both are available in two-door, four-passenger coupe and convertible body styles.

Standard equipment on the 640i coupe includes a turbocharged six-cylinder engine, 18-inch wheels, adaptive xenon headlights, LED foglights, adaptive suspension dampers, front and rear parking sensors, heated power-folding mirrors, a large tilt-only sunroof, keyless ignition/entry, heated six-way power front seats (with four-way lumbar adjustments), driver seat memory functions, leather upholstery, a heated power tilt-and-telescoping steering wheel, auto-dimming mirrors, dual-zone automatic climate control, adaptive cruise control and a rearview camera.

Electronic features include Bluetooth phone and audio connectivity, a 10.2-inch display, a navigation system, voice controls, the iDrive electronics interface, smartphone app integration and a nine-speaker sound system with a CD player, a USB interface and satellite and HD radio. 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 comes with those features plus a turbocharged V8 engine, 19-inch wheels, a 12-speaker surround-sound audio system and 16-way power front seats.

The optional Driver Assistance package adds side- and surround-view cameras, blind-spot monitoring, lane-departure warning and speed-limit information. The Executive package adds self-closing automatic doors, a power rear sunshade (650i coupe), ventilated front seats, leather-covered dash and contrasting stitching throughout, ceramic-trimmed knobs, a head-up display and smartphone integration. For the 640i models, the 16-way seats and surround-sound audio system are also included.

The Cold Weather package includes a heated steering wheel and a trunk pass-through ski bag. The Lighting package includes full LED lighting and automatic high beam control. BMW's Individual Composition options allow you to choose among various door sills, headliners, interior upholstery and trims, wheels and exterior trim.

The M Sport package adds unique 19-inch wheels, a sport steering wheel, a faux-suede headliner and an aerodynamic body kit. This year's 6 Series M Sport Edition is similar but further bundles the contents of the Lighting, Executive and Driver Assistance (650i only) packages.

Stand-alone options include active roll stabilization, active rear steer (rear-wheel drive only), 20-inch wheels, an infrared night vision display with pedestrian detection, adaptive cruise control, a 16-speaker Bang & Olufsen surround-sound audio system and an automated parallel parking system (rear-wheel drive only).

The 2014 BMW 640i is powered by a turbocharged 3.0-liter inline-6 that produces 315 hp and 332 pound-feet of torque. Rear-wheel drive and an eight-speed automatic transmission are standard across all models, and the xDrive all-wheel-drive system is optional. Thanks in part to an automatic stop-start system that shuts down the engine when stopped to save fuel, the EPA rates the 640i coupe at an impressive 25 mpg combined (22 city/32 highway) and the 640i convertible at 24 combined (20 city/30 highway). With all-wheel drive, the EPA says to expect 23 combined (20 mpg city/29 mpg highway) for both body styles. BMW estimates that a rear-drive 640i will go from zero to 60 mph in 5.3 seconds.

The 2014 BMW 650i is powered by a twin-turbo 4.4-liter V8 generating 445 hp and 480 lb-ft of torque. The V8 also uses an eight-speed automatic and comes with rear- or all-wheel drive. The EPA rates the rear-drive 650i coupe and convertible at 20 mpg combined (17 city/25 highway), and AWD 650i models are listed at 19 combined (16 city/24 highway). BMW estimates that a rear-drive 650i will go from zero to 60 mph in 4.5 seconds.

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 and active head restraints. Also standard is the BMW Assist emergency communications system (provides automatic crash notification and on-demand roadside assistance) and BMW Remote Services (further adds stolen vehicle recovery and remote door unlocking). Pop-up roll bars also come standard on the convertible. Optional safety equipment includes lane-departure and blind-spot warning systems, side- and surround-view cameras and a night vision display.

In Edmunds brake testing, the 650i coupe stopped from 60 mph in 109 feet and the convertible in just 111 feet. Both are about average for this class of car with summer tires.

Nail the gas pedal in the 2014 BMW 650i and the turbocharged V8 rewards you with wickedly quick acceleration. It might not seem like it given the car's overall smoothness, but only a handful of sports cars are capable of hanging with the 650i in a straight line. That said, the turbocharged inline-6 in the 640i is more than sufficient and will be a great choice for buyers as well.

While the 2014 BMW 6 Series is understandably not as sharp and agile as BMW's smaller, sportier 4 Series, its high levels of grip and composed nature are well suited for what we expect most drivers will want from a big grand touring car like this.

Although reasonably precise, the steering doesn't provide much in the way of feedback. This detail won't even register with most drivers, but if you've owned a BMW before, you might find the current 6 Series less engaging in this regard.

The 2014 BMW 6 Series interior is furnished with top-shelf materials in a close-fitting, cockpit-style environment. Depending on your preference, the prominent center console might instill a sense of security or slight claustrophobia. The iDrive electronics interface has a straightforward menu structure, crisp graphics and quick processing times, which helps minimize the amount of time you spend looking away from the road. That said, new owners should sit down and familiarize themselves with iDrive before hitting the road, because it's still a complex system and you can't master everything while the car's in motion.

The 6 Series excels at accommodating two passengers, but the rear seat is only suitable for adults on short trips. Trunk space measures 13 cubic feet for the coupe and a still impressive 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. The remarkable heat-reflective seats in the convertible work amazingly well.