A friend was over when the 2017 BMW B7 by renowned German tuner Alpina arrived, and as we ogled the luscious leather and mirror-buffed wood veneer seemingly covering every square inch of the cockpit, already we were drooling like two harbor cats eying an incoming fishing trawler.

"That's just … wow!"

"Know what's even better?" I asked my friend.

"There's better?"

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"It may look like a presidential suite but it can sprint from 0 to 60 mph in just 3.5 seconds." I passed my pal a red cup; the drool thing was getting serious.

The Alpina B7 is an utterly, thoroughly, conspicuously exquisite machine. Few automobiles radiate such an air of the sublime, from the finely stitched leather hides to the gleaming brushed-chrome trim to the sheer space and airiness of the five-passenger cabin (in a pinch, the ginormous back seat can carry three adults, but really it's set up for two to relax in regal splendor).

Alpina's B7 even out-shines BMW's own, similarly extravagant M760i; it's just even more artful and lovely inside. I mean, Alpina really sweats the details. Brush your fingertips on the backside of the steering wheel and you'll find not shift paddles (for the standard 8-speed automatic) but, instead, integrated, leather-covered pads for upshifts and downshifts. Further behind the wheel lies a 12.3-inch Alpina digital instrument cluster (laid out as analog dials) with a standard head-up display on the windshield. Just beauteous.

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But the true joy in driving the B7 is not simply being within its sumptuous embrace. No, the real draw lies under your right foot. Because there you'll find a twin-turbo 4.4-liter V-8 borrowed from the 750i—but amped-up with Mahle pistons, an Alpina intake system and intercooler, and up to 20.0 psi of boost. The result: 600 horsepower and 590 pound-feet of torque, up 155 hp and 110 pound-feet from the stock unit.

Mighty? Oh yeah: This mill just happens to make the B7 one of the quickest production automobiles BMW dealerships have ever sold. The maker claims a 0 to 60 mph time of just 3.5 seconds (though the B7 may actually be even quicker) and a top speed of 193 mph. This big beast (the thing is more than 17 feet long) would leave a Porsche 718 Cayman gasping in its wake.

Flattening the B7's go pedal is awe-inspiring, like being hurled from an invisible trebuchet, the all-wheel-drive system laying down the prodigious torque as the car rockets away in a furious rush of boost and dust and echoing exhaust. Yeah, a Tesla S P90D might be as quick or quicker off the line—but only for a few brief moments. Then its battery warms up and all the fun drains away. Not so in the B7. It keeps right on turning and burning, corner after corner, straight after straight. On an empty stretch of desert road, the speedo whirled past 140 mph like a normal car passing 40—and the B7 felt eager to keep right on going into the stratosphere. This is an insanely fast car.

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It's also a brilliant handler. Alpina has tuned the air suspension as if David Copperfield were in on the act, magically combining both a fluid ride and cornering grip far beyond what a vehicle this big theoretically should be able to deliver. Really, I'm not sure any other current BMW delivers chassis excellence at this level. The steering is accurate, the responsiveness quick and neutral, and stability simply superb. Unlike perhaps any other automobile on the market, the B7 manages to be both a limousine and a true sports sedan. It's an incredibly appealing dual personality at your command.

Naturally, such mechanical magnificence costs big. Base price for the B7 is $137,995. My test car also included such options as Bowers & Wilkins audio system ($3,400), Night Vision with pedestrian detection ($2,300), 21-inch Alpina wheels with performance tires ($1,300), and not one but two driver-assistance packages ($3,600 total). Final tally: $153,845.

Mind you, BMW's own new M760i xDrive is just as powerful as the B7—but it needs a twin-turbo 6.6-liter V-12 to do it. And it costs more, starting at $156,495 and easily climbing way past the sticker of my well-outfitted B7 tester. What's more, the B7 is quicker off the line, a lot faster (it's not constrained by a speed limiter like the M760i), and arguably even more delicious and luxurious inside. Anyone shopping for a top-end 7-Series absolutely owes it to themselves to check out Alpina's take on the formula.

Inscribed in a small metal plaque on the B7's center console are the words "Hersteller Exclusiver Automobile." I don't speak German, but I'm pretty sure that means, "Hang on. 'Cause this car will blow everything you think you know about sport sedans right outta your brainbucket."

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2017 BMW Alpina B7 xDrive Specifications ON SALE Now PRICE $137,995/$153,845 (base/as-tested) ENGINE 4.4L DOHC 32-valve twin-turbo V-8/600 hp @ 6,250 rpm, 590 lb-ft @ 3,000 rpm TRANSMISSION 8-speed automatic LAYOUT 4-door, 4-passenger, front-engine, AWD sedan EPA MILEAGE 16/24 mpg (city/hwy) L x W x H 206.7 x 74.9 x 58.7 in WHEELBASE 126.4.9 in WEIGHT 4,900 lb 0-60 MPH 3.5 sec (est) TOP SPEED 193 mph (est) Show All