BMW reveals Concept M4 coupe at Pebble Beach

BMW's M division has previewed its upcoming M4 coupe with the unveiling of a near-production-ready concept of the new performance coupe at the annual Pebble Beach Concours in Monterey, Calif.

The BMW Concept M4 provides a lightly veiled look at the eagerly anticipated M3 coupe replacement that is expected to make its public premiere in production guise at the Detroit auto show in January. North American sales will start before the second half of 2014.

As well as being used on the two-door coupe previewed by the Concept M4 coupe, the M4 name will also appear on a two-door M4 cabriolet as well as a new four-door M4 Gran Coupe due to reach US showrooms in 2015. The M3 name will survive on a four-door M3 sedan that is also planned to make its premiere at the Detroit auto show early next year and go on sale alongside the M4 in 2014.

The latest BMW M concept is billed as a design study that previews the appearance but provides few clues to the technical package of the M4 coupe.

However, BMW sources at the media presentation of the Concept M4 coupe confirmed to Autoweek the new M-car will adopt inline six-cylinder power, bringing an end to the reign of the high-strung V8 used by the last M3 after a run of just six years. Known internally under the codename S55, the newly developed twin-turbocharged 3.0-liter straight six is claimed to kick out around 450 hp, versus the 420 hp of the current naturally aspirated 4-liter V8.

Drive will be channelled to rear wheels through the same seven-speed dual clutch gearbox used by the more powerful 560bhp twin-turbocharged 4.4-litre V8 powered M5 sedan and M6 coupe, cabriolet and GranCoupe.

Nothing is official just yet, but BMW insiders hint the M4 coupe will accelerate from 0-to-62 mph in under 4.5 seconds and reach a top speed limited to 155 mph.

As expected, the M4 receives a significantly more aggressive appearance than the recently introduced 4-series upon which it is based and will be produced at BMW's plant in Regensburg, Germany.

The heavily redesigned front-end receives a deeper and more structured bumper with a prominent carbon-fiber splitter element to slice the air, and larger air ducts to cool the engine. Other elements include a blackened kidney grille, complex LED imbued headlights, more heavily flared front fenders, a traditional "powerdome" within the bonnet and air intakes in the front wheel arches to extract hot from the carbon ceramic brakes.

At the rear are wider fenders to house substantial rear wheels and tires, a new trunk lid with a more pronounced lip for added downforce at speed, a heavily redesigned bumper and a quartet of carbon-fiber tailpipes.

The Concept M4 coupe showcases lightweight 20-inch cast-alloy wheels in BMW M division's familiar double spoke design. Other lightweight materials within the body include a carbon-fiber-reinforced-plastic roof and rear diffuser. In combination with aluminum body panels they are said to bring the production M4 coupe to around 3,300 pounds -- about 400 pounds lighter than the current M3 Coupe.

BMW hasn't yet shown the M4 coupe's interior, but officials suggest it will receive all the traditional touches of more recent M division models, including revised instruments along with an M-specific steering wheel, seats and trims – all trimmed in a combination of leather, Alcantara and carbon-fiber.

By Greg Kable