BMW Debuts 2015 M3 Sedan and M4 Coupe
By: Jeff Youngs, 12/13/2013
At the heart of the transformation is a new twin-turbocharged, 3.0-liter, inline 6-cylinder engine boasting enhanced cooling and oil-supply systems engineered to endure aggressive runs on the track, variable valve and camshaft timing, and direct injection. Output measures 425 horsepower between 5,500 and 7,300 rpm, along with 406 lb.-ft. of torque that's available between 1,850 and 5,500 rpm. Redline is 7,600 rpm. For comparison, the previous M3's naturally aspirated 4.0-liter V-8 was about 22 lbs. heavier and generated 414 horsepower backed by 295 lb.-ft. of torque. BMW claims the 6-cylinder is roughly 25% more efficient, which would equate to EPA fuel-economy ratings of 17/25/20 mpg (city/highway/combined).
Transmission choices include a standard 6-speed manual with new synchronizer rings and a downshift rev-match feature, and a 7-speed double-clutch automated manual gearbox with launch control, redesigned paddle shifters, and various modes that can be selected to suit a driver's style or current travel conditions.
Complementing the 2015 M3 and M4's new powertrain are curb weights that have been reduced by about 175 lbs., a feat accomplished in part by the generous use of aluminum and carbon-fiber-reinforced polymer (CFRP) throughout the car, including a standard CFRP roof.
Collectively, these efforts allow the M3 and M4 to reach 60 mph in as little as 3.9 seconds, according to BMW. Top speed is electronically limited to 155 mph. Drivers who want to gauge how well they're doing behind the wheel can download a free BMW M Laptimer app that tracks lateral acceleration, engine revs, steering angle, and more, with results presented as a graphic display on the user's smartphone.
Also contributing to the 2015 models' performance are an upgraded chassis and key aerodynamic enhancements. Among the highlights are a forged-aluminum suspension with a new 5-link rear axle, electromechanical power steering that includes three settings (comfort, sport, sport+), M-specific compound brakes, electronic limited-slip differential, massive front air intakes linked to "gills" located behind the front wheels, integrated CFRP rear spoiler (M4), and lightweight 18-inch alloy wheels. Options include ceramic brakes, an adaptive suspension, and 19-inch alloy wheels.
Inside, the 2015 M3 and M4 are equipped with unique door sills and gauges, as well as new racing-inspired front bucket seats fitted with an illuminated "M" logo. Rear passengers get their own deeply contoured seats, which fold down to increase cargo space. Other amenities include an updated navigation system with 3D maps, head-up display, pedestrian-alert safety system, and LED headlights.
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