Revolutionizing the BMW M3

BMW is less than a year away from officially revealing the fifth generation of the menacing M3, the first to receive turbocharged six-cylinder power.

The performance sedan, code-named F80, is expected to appear as a lightly veiled concept at the 2013 Geneva motor show, debuting the appearance and mechanical package of the M division's eagerly anticipated Mercedes-Benz C63 AMG rival. A showroom-ready version with a production interior arrives at next year's Frankfurt motor show, BMW sources say.

If this timeline holds, the next M3 should be ready for North American sales in winter 2014 at prices that likely will top the $60,995 sticker of the 2012 M3 coupe, owing to the car's higher positioning and greater levels of standard equipment. The last version of the M3 sedan went out of production in October 2011.

In a departure from previous generations, this M3 will be launched exclusively as a sedan, a move that brings it in line with the larger and more expensive M5. Several sleeker-styled models—including a follow-up to today's coupe and cabriolet—will then be added to lineup, which will be supplemented by a Gran Coupe variant. But, as part of a different naming process, it will eschew the M3 name for M4 nomenclature.

The M3 sedan will follow the example of the larger M5 in receiving a host of functional but subdued styling changes in comparison with the standard 3-series sedan. This means a deeper front bumper with large cooling ducts for the forced-induction engine, a lightly altered kidney grille, wider front fenders with the signature air vents, unique exterior mirrors and wider door sills. In back are a subtle trunk-lip spoiler and a deeper rear bumper that incorporates a diffuser to cool the rear differential.

Despite BMW's increasing commitment to carbon-fiber construction, the M3 will retain a steel platform structure, though certain parts of the body shell, including its hood and doors, will be fashioned from aluminum.

While the turbo straight-six is set, rumors to the contrary have been flying about the M3's mechanical package, with some even suggesting that the car would receive a 3.3-liter V6 engine based around the 90-degree architecture and cylinder capacity used for the larger M5's 4.4-liter V8 engine.

“This is utter rubbish,” a high-ranking source said. Packaging considerations aside, there is no reason for BMW to abandon its tradition of straight six-cylinder power—neither from a performance nor a production standpoint.”

But purists might still question the decision to go with a turbocharged engine that will bring an end to an illustrious era of naturally aspirated powerplants for the M3. Additionally, for the first time since its inception in 1986, there will be no manual gearbox.

In a bid to match the performance levels offered in top-shelf Mercedes and Audi products, the engine in the BMW is expected to deliver about 450 hp and 350 lb-ft of torque. By comparison, the 2012 M3 makes 414 hp and 295 lb-ft of torque from a naturally aspirated 4.0-liter V8.

The next generation will come with a standard seven-speed dual-clutch gearbox, similar to the transmission in the M5 but with altered ratios, offering both manual and automatic modes. Power will be sent to the rear wheels via an electronically controlled variable M differential, offering 100 percent lockup.

Plans for an all-wheel-drive version of the car were considered but rejected. Instead, BMW is planning to introduce an M335i with all- and rear-wheel drive as part of its new M Performance lineup.

Underpinning the M3 will be an aluminum-intensive chassis with a longer wheelbase and wider track than today's model, giving the car a significantly larger footprint. We don't have all of the final specs on the next-generation M3, but it's safe to say that this sedan will be an agent of change for BMW performance machines.

By Greg Kable