In Detroit, BMW powers up, doubles down on M badge

Balance was restored to the performance car universe on 13 January in Detroit, as BMW brought its signature in-line six-cylinder engine back to life in the M3 sedan and M4 coupe.

The cars were introduced to the press with crackling exhaust from a squirt of throttle, as BMW board member Ian Robertson drove the coupe model onto the stage at Cobo Center.

The outgoing car was propelled by a near race-spec V8 engine that, however thrilling, was a non-traditional choice for the M3. The new car’s 3-litre six-cylinder unit weighs 22lbs less than the V8 and uses twin turbocharging to crank out 431 horsepower and 406 pound-feet of torque, increases of 17hp and a shocking 111lb-ft over the outgoing V8.

"Today at the Detroit auto show is all about M," Robertson said in his introductory remarks. "It sets new standards in overall concept, precision and agility."

M cars put power to pavement exclusively through the rear wheels – no all-wheel drive here. The Active M Differential lets drivers enjoy the rear-wheel drive as never before, as its control unit, combined with the stability control computer, considers accelerator pedal position, wheel speed and yaw rate when deciding how much to lock the multi-plate limited-slip differential. It can vary anywhere from fully open, with no connection between the left and right wheels, to 100% lock, when they turn at exactly the same speed. The computer control of this critical device contributes to improved corner turn-in as well as acceleration at corner exit, added BMW test driver Bruno Spengler.

Available transmissions are a conventional six-speed H-pattern manual equipped with automatic rev matching for downshifts, and a seven-speed dual-clutch automatic.

Both cars are longer, lower and wider than their predecessors, though the fundamental proportions of the 3 Series and 4 Series models on which they are based are unchanged. BMW designers have, however, added a deep front air dam that is aerodynamically balanced by a spoiler at the rear and connected by a smooth belly pan.

The M cars’ suspension uses plenty of aluminium for reduced mass and weight, and the front strut tower brace is carbon fibre composite for the same reason. For enthusiasts who loved the carbon fibre roof available on higher specifications of the old M3 coupe, the feature is now found on both two- and four-door models.

The overall slim-down trimmed 176lbs from the M4, compared with the previous M3 coupe. Pricing for North America will have to wait until closer to the M3 and M4’s arrival in dealer showrooms, set for June. In Germany, the M4 will command 72,200 euros (about $99,000) – which is a notable 6,550 euros (about $9,000) less than its archrival, Audi’s 450hp RS5. Naturally, BMW claims the new cars top the stellar track performance of the outgoing M cars, but confirmation must wait until later in the year, when we are invited to re-create Robertson’s throttle blips on an open circuit.