BMW M Steps Up Technology With Upcoming Coupe, Sedan

MUNICH – BMW is committed to reaffirming and advancing its leadership in the profitable performance-car sector, as it prepares for the launch next summer of its all-new M4 Coupe and its fifth-generation M3 sedan in 28 years.

Reversing the traditional approach where the coupe follows as a derivative of the sedan, the 2-door M4 is leading the charge with the 4-door M3 to come later.

Since the launch of its first M3, back in 1984, BMW has been the undisputed leader in the high-performance premium sport niche, but the pressure applied by strong rivals Mercedes-Benz AMG and Audi RS is causing the Bavarian automaker to up its game in both design and engineering.

The new M4 Coupe checks in at less than 3,307 lbs. (1,500 kg), some 176 lbs. (80 kg) lighter than a comparably equipped M3 Coupe, providing obvious driving-dynamics and fuel-efficiency advantages.

Helping slash weight is the switch from a 4.0L V-8 to an all-new 3.0L inline-6 that brings the car back to its roots. The second- and third-generation M3s also were powered by 6-cyl. engines.

The new powerplant is turbocharged and creates roughly 25% more power and torque than the larger, outgoing V-8. Output is said to hit 429 hp and surpass 369 lb.-ft. (500 Nm) in maximum torque.

Even more relevant is how quickly peak torque is reached, at 1,900 rpm, and how long it is maintained, beyond 5,000 rpm.

These are not official figures. BMW M so far has been secretive about actual output numbers, in part because the new M3 and M4 remain under development. But BMW’s performance division also isn’t in a hurry to give its competitors an advance look at the new benchmark they will have to beat.

For the time being, engineers appear most proud of the inline-6’s tailpipe performance, where carbon-dioxide emissions are held below 200 g/km, better than those produced by the 2.3L 4-cyl. under the hood of the first-gen M3. The new powerplant will meet Euro 6 emissions standards, the automaker says.

“The engine is the heart of every M model, and the example fitted in the two new cars combines the virtues of a high-revving naturally aspirated unit with the strengths of turbocharger technology,” says BMW M President Friedrich Nitschke.

The lighter, more compact 6-cyl. is only the starting point of a new high-efficiency era under way at BMW M, which also is on the verge of launching a 2.0L 4-cyl. that will power the smaller M2 coupe set to challenge the recently released Mercedes-Benz CLA.

The performance arm’s new holistic development philosophy seeks to reduce the weight of the entire car by integrating more functions into as many components as possible, rather than simply switching to lighter metals and materials.

One clear example is the new M4’s trunk lid, which combines optimal design with aerodynamic efficiency, as well as saves some 12 lbs. (5.5 kg) thanks to its carbon-fiber-reinforced plastic structure and sheet-molding compound skin.

BMW traditionally targets a 50/50 weight distribution front to rear, meaning the M4 strategy called for reducing weight on the front axle “at any reasonable cost” and balance at the rear axle.

The weight savings on the upper part of the body created by the new trunk lid, as well as a CFRP roof, allowed engineers to add some mass in linking the body to the rear-axle subframe. That gives the car a lower center of gravity for improved handling.

The use of CFRP also allows designers to get more creative while satisfying weight, aerodynamics and cooling requirements. Although the large air intakes at the front end and diffuser at the muscular rear have their jobs to do, they also serve as key design elements for the car.

CFRP is used for the car’s driveshaft as well, and the material’s tremendous stiffness allows for the unit to be constructed in a single piece, with no central bearing. Its 40% weight savings over its predecessor reduces rotating mass, allowing power to be transferred more quickly from engine to rear axle.

The cars have additional high-tech features, but BMW isn’t releasing complete details this far in advance of market launch.