BMW goes back to six for M3 sedan and M4 Coupe, will debut in Detroit

BMW’s venerable M3 is losing two cylinders, but drivers won’t notice any loss of power.

After introducing a V-8 for a single generation in the outgoing coupe, convertible, and sedan models, BMW has reverted to the traditional straight six - now with turbochargers - for its 2015 M3 sedan and M4 coupe.

“Four generations of the BMW M3 have blended motor sport genes and uncompromised everyday usability within an emotionally rich overall concept,� said Friedrich Nitschke, president of BMW’s M division. “The BMW M3 Sedan and BMW M4 Coupe represent an ongoing commitment to this philosophy.�

PHOTOS: BMW’s 2015 M3 and M4

The fifth-generation duo will make their world debut at the 2014 Detroit Auto Show in January.

Under the bulging aluminum hood of each sits a 3.0-liter, twin-turbocharged inline six-cylinder engine. Horsepower bumps up modestly over the previous version to 425 total, while torque is up considerably to 406 pound-feet. Redline is a relatively high 7,600, considering this is a turbocharged engine.

The rear-wheel-drive coupe and sedan will be able to sprint from zero-60 mph in 4.1 seconds with the standard six-speed manual transmission, BMW said. Cars with the optional seven-speed dual-clutch automated manual will do the same run in 3.9 seconds.

Both the M3 sedan and M4 coupe are about 176 pounds lighter, due in part to the use of carbon fiber for the roof, and aluminum in various body panels and suspension components. The swap from a V-8 to a turbocharged, inline six-cylinder engine saved 22 pounds.

This lighter weight helps the M3 and M4 boost their fuel efficiency by roughly 25% over the outgoing iterations, BMW said. Other performance goodies include an electronically controlled limited-slip differential, a track-ready oil cooling system, and throttle blipping on the manual gearbox and launch control on the automated manual.

Built since 1986, the M3 is a high-performance version of the more sedate 3-Series. The first generation M3 was an instant hit, selling nearly 18,000 copies worldwide during its five-year run. The car has been crucial to promoting BMW’s ethos of driver-oriented machines, and often has enthusiast magazines tripping over themselves to find new ways to praise the car.

The 2015 model year will be the first that BMW has delineated the coupe and sedan versions with different badges. Until now, the coupe, convertible, and sedan (which BMW hasn’t always built) all used the M3 name. Yet the automaker is now separating its sedans from its coupes and convertibles across its lineup. The 4-Series coupe and convertible is based on the 3-Series, thus the M4 is based on the M3.

The two models will go on sale in the middle of 2014. Pricing will be announced closer to the on-sale date.

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