M4 GTS On Way, But Supplies Limited

STUTTGART – The BMW M4 GTS is headed for production. But buyers will need to be quick to snare one.

Just 700 examples of the powered-up performance coupe, which debuted in lightly veiled concept form at the Pebble Beach Concourse d’Elegance in August, are planned to roll from BMW’s Regensburg production line in Germany.

Of those, less than half are allocated to the U.S. market, where deliveries are slated to begin in March.

Significantly, the M4 GTS is the first of BMW M division's more recent special-series models to be made available to U.S. buyers, signaling the growing importance of the North American market to the automaker’s long-revered performance-car operation.

Headlining the long list of performance-enhancing changes made to the standard M4 coupe in the creation of the limited-volume GTS is the adoption of a reworked version of BMW M division’s twin-turbocharged 3.0L straight-6 gasoline engine.

The aluminum-block unit uses a new water-injection process that also is being readied for inclusion on more mainstream engines used in higher volume models, reveals Klaus Froehlich, BMW board member responsible for R&D.

Tested extensively on prototype versions of the new 2-door coupe as well as the M4 MotoGP safety car in service at this year’s MotoGP championship, the water-injection process sprays a fine mist into the intake manifold to lower the temperature of the incoming air.

In turn, the temperature within the combustion chamber is lowered, reducing the knock threshold and allowing BMW’s M division to provide the M4 GTS’s engine with higher turbocharger boost pressure than that used by the standard M4.

The first-ever water-injection system to be included on a series production BMW model consists of three individual injector units sited in the intake plenum chamber – each of which supplies water to two of the engine’s six cylinders. A pump delivers water to the injectors from a 169-oz. (5L) tank located in the trunk at a pressure of 145 psi (10 bar), the quantity varying depending on load, revs and temperature.

BMW says the water tank needs topping up at every fifth gasoline refilling stop under normal driving conditions. Under hard driving on a track, however, it advises the M4 GTS’s water tank be topped off at each refueling.

Further engine changes include the adoption of a new titanium exhaust system with larger diameter tailpipes, providing reduced back pressure.

The result is a 16%, or 68-hp, increase in peak power, with 493 hp delivered at 6,250 rpm. This provides the 3,329-lb. (1,510-kg) M4 GTS with a weight to power ratio of 6.75 lbs. (3.1 kg)/hp – a 1.2-1b. (0.5-kg)/hp improvement on the standard 3,384-lb. (1,535-kg) M4 coupe.

Torque also has risen 10%, or 37 lb.-ft. (47 Nm) to 442 lb.-ft. (599 Nm) from 4,000-5,500 rpm.

With its increased reserves channeled through a standard 7-speed dual clutch gearbox, BMW claims the rear-wheel-drive M4 GTS reaches 62 mph (100 km/h) from standstill in 3.8 seconds, shaving 0.3 seconds off the time of the standard M4. Top speed also increases 40 mph (64 km/h) to a limited 190 mph (306 km/h).

Retaining the same dramatic styling as the earlier concept car, the production version of the M4 GTS receives a series of lightweight components that help to pare some 55 lbs. (25 kg) from the weight of the standard M4 coupe, including a hood, front splitter element, roof, adjustable rear spoiler mounted atop the trunk lid, rear diffuser and instrument-panel bracing tube fashioned from carbon-fiber-reinforced plastic.

The new BMW also receives new organic LED (OLED) taillamps, making it the first production car to do so.

Further modifications are focused on the chassis, with the inclusion of coil over springs offering adjustable compression/rebound rates and larger diameter antiroll bars attached to altered support mounts for added rigidity.

The forged and polished orange wheels are taken over directly from the earlier concept car.

As a measure of the dynamic ability of the new M4 GTS, BMW claims it is capable of lapping the notorious Nürburgring circuit in Germany in 7 minutes, 28 seconds, a time, BMW M division sources suggest, places it more than 10 seconds ahead of the standard M4.

Pricing for the M4 GTS has not been announced. The standard M4 coupe retails for $65,400.