2011 BMW Alpina B7 - Chicago Auto Show

Avoiding the crowded schedule of the Detroit auto show, BMW made the North American debut of the Alpina B7 luxury sport sedan at the Chicago auto show with an intimate briefing of a handful of journalists rather than a typical amped-up pyrotechnic auto show introduction.

The low-key approach suits the Alpina, which in hot-rod parlance is a classic "sleeper." That means this baby boasts 500 twin-turbo horsepower under hood that rockets the mammoth 7-series luxury sedan-based model to 60 mph from a standstill in just 4.5 seconds.

The engine wears a pair of 44-mm turbochargers, which cool their intake charge with a trio of intercoolers. A main low-temperature intercooler mounts near the radiator and a near-engine intercooler mounts near each turbo. This contributes to the engine's ability to withstand 15 psi of boost with 9.2:1 compression.

The most obvious visual clue to this car's status as something more than a run-of-the-mill 7-series is its use of the 20-spoke wheels that are the signature styling cue of the Alpina tuning shop.

The company determined decades ago that 20 spokes provide, in its view, the optimal balance between weight and strength. Whether or not this is still true is irrelevant; Alpina fans expect this detail in the company's cars. Their lightweight design permits the B7's 21-inch wheels to weigh no more than the 18-inchers fitted as standard equipment on the 7-series, according to Alpina.

There are also small spoilers adorning the B7 that are additional subtle clues to the car's true nature. The front splitter integrates the vents for cool air to the transmission and engine oil coolers, slashing lift at the front of the car by 30 percent. A modest trunk lid spoiler trims rear lift by 15 percent, and the overall lift is sufficiently reduced to confer greater confidence-inspiring stability at autobahn speeds.

 

See more photos:
2011 BMW Alpina B7 Gallery

 

Build and price your new BMW. 

Explore all the new BMW models in the New Model Showcase.

Find your new BMW for sale. 

 

About the Author
Dan Carney is a veteran auto industry observer who has written for MSNBC.com, Motor Trend, AutoWeek, The Wall Street Journal, The New York Times, Popular Mechanics, Popular Science, Better Homes and Gardens and other publications.  He has authored two books, "Dodge Viper" and "Honda S2000" and is a juror for the North American Car of the Year award.  Carney covers the industry from the increasingly strategic location of Washington, D.C.