A full-size luxury sedan with "green" credentials is an intriguing proposition, and the 2014 BMW ActiveHybrid 7 presents, at least at first glance, plenty of intrigue. After all, it's derived from BMW's conventionally powered 7 Series and adds an appealing 25 mpg combined fuel economy rating (and 30 mpg on the highway). But the devil, as they say, is in the details.

Although the 2014 ActiveHybrid 7 does deliver all the intrinsic sport-oriented driving characteristics and interior luxury that have always made the 7 Series hold its place among large "flagship" sedans, its extra cost compared with the conventional 740Li (22 mpg combined) would take a new owner about two decades to recover in fuel savings alone. If you're considering an ActiveHybrid 7 to save money, you'd better be in it for the long haul.

Then again, some might look at the price premium for the ActiveHybrid 7 as just another kind of tech option -- one that does happen to reduce fuel consumption.  And apart from whether the 2014 ActiveHybrid 7 makes a business case for itself, the car itself can be a rewarding, responsive driving partner and certainly delivers the full experience of BMW's distinctive blend of cool and cabin luxuries.

Of course, there are other choices. Porsche's 2014 Panamera Hybrid is even sportier than the ActiveHybrid 7, but considerably costlier. Lexus also charges more for the less-efficient 2014 LS 600h L. Audi doesn't offer a hybrid with its A8, but the diesel-fuelled 2014 A8 3.0 TDI model actually offers the best fuel economy out of all of these sedans. Overall, the ActiveHybrid holds its own as hybrid flagships go, but from our standpoint the Audi would be a better choice if you want the best green credentials.

The 2014 BMW ActiveHybrid 7 comes standard with 18-inch wheels, adaptive suspension dampers, adaptive xenon headlights, LED foglights, power-folding and heated mirrors, a sunroof, keyless ignition and entry, front and rear parking sensors, auto-dimming mirrors, cruise control, four-zone automatic climate control, leather upholstery, a power tilt-and-telescoping steering wheel, heated power front seats and driver memory functions. Electronic features include a rearview camera, BMW's iDrive interface, a navigation system, Bluetooth and a 10-speaker sound system with HD and satellite radio, a USB/auxiliary audio port and iPod integration.

On top of this, buyers can choose among several options packages. The Cold Weather package adds heated rear seats and a heated steering wheel. The Executive package includes a power trunk lid, power soft-closing doors, a head-up display, 14-way power "Multicontour" front seats, ventilated front seats and a 16-speaker premium sound system.

Also available is the Lighting package with LED headlights with automatic high beam control. The M Sport package features aerodynamic body enhancements, a higher top speed and a sport steering wheel with paddle shifters. The Driver Assistance package adds a lane departure warning system, blind spot monitoring, side and top view cameras and a speed limit display. For rear-seat passengers, there's the Luxury Rear Seating package (power-adjustable and ventilated rear seats with massaging functions) and the Rear Entertainment package (two rear monitors, a rear iDrive controller with touchpad and six-DVD changer).

Stand-alone options include 19-inch wheels, an automatic parallel parking system, adaptive cruise control, night vision and a premium Bang & Olufsen sound system. Numerous optional interior treatments include a steering wheel with wood inlays, power rear sunshades, front seat massage functions, ceramic-trimmed control buttons and additional leather surfaces.

The 2014 BMW ActiveHybrid 7 comes with a turbocharged 3.0-liter inline six-cylinder engine that is paired with an electric motor powered by a lithium-ion battery pack. Combined, the gasoline engine and electric motor produce 350 horsepower. An eight-speed automatic transmission is standard and sends power to the rear wheels.

BMW estimates the sedan will accelerate from a standstill to 60 mph in 5.5 seconds. The EPA estimates fuel economy at 25 mpg combined (22 mpg city/30 mpg highway). For comparison, the regular 740i has a combined estimate of 22 mpg.

All 7 Series models come standard with antilock brakes, traction and stability control, front side airbags, full-length side curtain airbags, front knee airbags and active front head restraints. Also standard is the BMW Assist emergency communications system, which includes automatic crash notification, an emergency response button, remote door unlock and stolen vehicle recovery. Multiple parking cameras, a blind-spot warning system, a lane-departure warning system, a drowsiness monitor and a collision mitigation system with automatic braking are available (mainly via the Driver Assistance Plus package).

Don't expect the 2014 ActiveHybrid 7 to perform much differently from the standard BMW 7 Series. Unlike the gasoline-only 7 Series, though, the 740Li Hybrid can glide silently on electric power only. The caveat, however, is that it takes a very light throttle application and range is limited to a maximum of 2.5 miles at a top speed of 37 mph. Selecting the EcoPro mode helps in this regard by dialing back performance and responsiveness in favor of fuel economy.

Odds are the ActiveHybrid 7 will not disappoint those seeking a confident, comfortable long-distance cruiser. The ride is comfortable yet composed, there's plenty of room for four inside, and the different drive settings allow each driver to set the car to reflect individual preferences.

BMW has almost always resisted the latest trends in dashboard design, sticking instead with classic gauges and an understated center stack that cants toward the driver. There's undeniable appeal in that, but the downside is the lack of differentiation between the 7 Series and the ostensibly lesser 5 Series. The dashboards aren't identical, but they're pretty close, and that's one fewer reason to consider the 7 Series special. Even the iDrive infotainment system's slick new touchpad with fingertip-scribble recognition isn't an exclusive feature; it's standard on many other BMWs this year, too.

Still, you're not exactly slumming it in this BMW. The 7's supple leather, rich wood accents and other high-quality materials assure a suitably premium feel. Comfort is pretty much beyond reproach, especially if you opt for the multicontour front seats with their incredible support and range of adjustments. The rear seats are plenty spacious, and the available power rear seats with heating, cooling and massage provide further incentive to let someone else ride shotgun.

The extra hybrid components rob the ActiveHybrid 7 of some useful trunk capacity, however. Cargo space is a rather scanty10 cubic feet.