Photos copyright ©2011 Michael Harley / AOL

Headquartered in Germany, Alpina Burkard Bovensiepen GmbH ("Alpina") has been working its magic on BMW models since the 1970s, and while most think of Alpina as an aftermarket tuner, the company is officially recognized as an automobile manufacturer. From its earliest days, Alpina models have been noted for their factory-quality engine, suspension and cosmetic upgrades, and the company is credited with offering high-performance street variants of BMW models even before the automaker's own Motorsport "M" Division jumped into the game.Thirty-five years later, I'm sitting behind the wheel of an F01 B7 BiTurbo – Alpina's latest creation, based on BMW's current 7 Series platform. Mirroring the various chassis and powertrain options offered by BMW, the Alpina B7 can be had in standard- or long-wheelbase, and with rear- or all-wheel drive (xDrive). The sportiest variant of the four is the short-wheelbase, rear-wheel-drive model. That would be the Alpina Blue Metallic model we're piloting.The heart of every Alpina model is the hand-crafted engine, and the B7 is fitted with a highly modified version of BMW's N63, the all-alloy direct-injected 4.4-liter twin-turbo V8 currently fitted to the BMW 750i . Craftsmen at Alpina's facility in Buchloe, Germany are tasked with opening it up and performing a delicate surgery that includes a slew of upgrades and enhancements for the entire powertrain. High-performance pistons are inserted into the block and the cylinder heads are reinforced to withstand the additional stress from a higher compression ratio. A larger intercooler, with a 35-percent increase in surface area, is fitted to lower intake temperatures. An additional radiator lowers coolant temperatures, and external coolers are added for the engine and transmission oil. The electric fan is also upgraded to increase airflow through the new high-performance components. To move more oxygen through the engine, larger turbochargers (the vanes measure 44 mm in diameter) are fitted to keep the whole package running smoothly and Alpina engine management software increases boost to 14.5 psi and recalibrates both stability- and traction-control with more aggressive settings.While the 750i's N63 develops 400 horsepower and 450 pound-feet of torque, the modified twin-turbocharged 4.4-liter V8 in the Alpina B7 jumps to 500 horsepower and 516 pound-feet of torque – raising specific output to 115 horsepower per liter.Accommodating the power is Alpina's "Switch-Tronic" gearbox (a modified ZF wet six-speed automatic). Tiny leather-covered buttons on the back of the steering wheel allow manual gear selection (right side "+" and left side "-") and the driveline, from driveshaft to differential, has also been strengthened.The suspension architecture utilizes BMW's Dynamic Damping Control and Active Roll Stabilization, as found on other 7 Series models, but Alpina wouldn't be expected to leave it alone. The automaker increases spring rates by 20 percent and lowers ride height by about half-an-inch overall. From the cockpit, the driver is able to select from three suspension setups: Comfort, Normal and Sport. Sport-Plus mode shifts the Dynamic Stability Control system into a more aggressive Dynamic Traction Control (DTC) setting, allowing more slip at the driven wheels and reducing the interference of the traction control system.Massive brakes (sourced from the heavier armored 7 Series "Protection" model) measure 14.72 inches in diameter up front and 14.57 inches in the rear. The standard wheels are Alpina-designed 21-inch alloys (the valve stem is in the center, thanks to a single hollow spoke) wearing 245/35ZR21 tires up front and 285/30ZR21 tires in the rear (xDrive and long-wheelbase models are fitted with 245/50ZR18 tires on all four corners). The curb weight of this rear-wheel-drive standard-wheelbase model, according to Alpina, is 4,564 pounds and opting for the long-wheelbase xDrive model causes the curb weight to balloon to 4,861 pounds. Regardless, the standard B7's weight distribution is a fairly balanced at 51.4:48.6 front-to-rear.The exterior of the B7 is distinguished by unique twin double tailpipes and its special front and rear lower spoilers. Alpina says the latter reduce lift by 30 percent at the front and 15 percent at the rear, and improve high-speed stability without adversely affecting the drag coefficient. We say they look far too "tacked-on."The interior of the Alpina B7 receives its own touches. The cabin is upgraded with sport seats (covered in special Alpina leather), new instrument faces (red needles over a blue background), "Myrtle" wood trim, Alpina floor mats, branded illuminated door sills, and a hand-stitched Alpina steering wheel with the unique aforementioned button shifters. Lastly, if someone has somehow missed all of the other markings, there is one last Alpina plaque mounted on the inner roof panel just ahead of the moonroof.Superfluous branding aside, the cabin of the B7 is one very comfortable place to pass extended periods of time (think BMW 7 Series, but with an extra dollop of luxury and amenities). It's hard to fault the seat comfort, support, driving position or overall presentation.With a push of the start button, the engine spins over and settles to a muted idle, although surprisingly, there's nothing noteworthy about the exhaust note. Like all 7 Series sedans, the B7 feels big. Backing up is accomplished with the help of electronic aids, and lane changes require a deliberate look over the shoulder followed by a second glance in the mirror. While it's entirely competent in a metropolitan setting, the full-size sedan simply feels a bit out of place lazily trudging along the boulevard.Want to wake a sleeping giant? Press the accelerator pedal to the floor.Alpina's blown 4.4-liter comes to life like a cadet springing out of bed for a drill sergeant's call. Any thoughts of turbo lag are slammed to the back of the brain (and forgotten) as the B7 takes off. Yes, it's big and heavy, but it gets out of its own way with authority. BMW quotes a 0-60 sprint in 4.5 seconds, but it feels quicker (just for grins, we hooked the B7 up to a rather simple Escort G-Timer GT2 and recorded an easy 4.32 seconds). As a sucker for brutal power, we are happy to declare that this Alpina sedan hits all the right nerves. Like a Nissan GT-R , the B7 absolutely begs to show off at stoplights.Place the B7 on an open highway, and pavement rolls quietly under its chassis mile after mile. However, it's difficult to finger another five-place full-size luxury sedan that is as adept off the highway on fun two-lane roads.Alpina's decades of experience working hand-in-hand with BMW has delivered. The suspension tuning is just about perfect, with very little body roll and nearly fault-free damping on most road surfaces. Directional changes are quick and fluid, with great feedback through the steering wheel. While we didn't like the tiny shift "buttons" on the back of the steering wheel (nearly useless in the heat of battle), the six-speed auto was competent when the car was set in "Sport-Plus" mode – come to think of it, the B7 could really use one of those trick "M" buttons to personalize performance parameters.The Alpina B7 is an amazing machine. Defying all logic, the sedan seems to shed pounds as the g-forces increase – the uncanny feedback from the driver's seat is of a sports car wrapped in a lightweight paper-mâché 7 Series disguise. In a word: fun.The good news is that the Alpina B7 earns the fur-lined gold crown as the current high-performance king of BMW's big sedans. And, with the E60 M5 out of production and the F10 M5 still a few months away, it should be able keep its head warm until summer arrives. Don't forget, with a base price of just $122,000 the B7 also comfortably undercuts the $137,000 twelve-cylinder twin-turbo 760Li.The bad news for the Alpina B7, of course, is that rival Mercedes-Benz has just updated the engine in its high-performance $138,000 S63 AMG . Gone is the naturally-aspirated 507-horsepower 6.3-liter V8. In its place is a new twin-turbocharged 5.5-liter V8, rated at 536 horsepower and 590 pound-feet of torque (opt for the $7,300 Performance Package, and those numbers soar to 563 horsepower and 664 pound-feet of torque). When it comes to powerplants, the new S63 AMG engine is about as good as they come, but the S-Class ' overall performance package still falls short of the B7. Put another way, nobody races an S63, but more than a handful of Alpina owners frequent the track – with hardly a laugh from the peanut gallery.The M3 Coupe is a better sports car, but on this particular day and on this specific road, the other driver will never be able to prove it. Each time he shoots into a corner, we follow 20 yards back. He opens the gap at every apex, but we're hard on the throttle to close it after each exit. He just can't win.If there is any consolation to the M3 owner, it's the fact that Alpina will only be assembling about one thousand of its 7 Series sport sedans each year. Less than half of those will arrive in the States. This should be a comfort to that special breed of sport coupe drivers as they will seldom ever see an Alpina B7, let alone be intimidated by one on a lonely canyon road.