What's the news?

It's still a month before we drive the all-new BMW M3 Saloon and M4 Coupé for the first time, yet there's already a new variant to consider. Say hello to the M4 Convertible, making its world debut at the New York Auto Show later this month.

Exterior

Aggressive yet stylish would probably be the best way to describe the M4 Convertible, sort of like taking an MMA fighter and fitting them out with a perfectly tailored suit straight from Saville Row. Signature M identifiers like the power dome on the bonnet and flared arches front and rear are the muscles to the exquisitely cut roof-folding mechanism, which, thanks to the loss of the B-pillar, leaves an uncluttered profile when driving al-fresco.

Forged alloy wheels serve as the rolling stock with 18-inch units as standard and 19s available from the options list. Like its Saloon and Coupé siblings the M4 Convertible sports some trick aerodynamics such as the lift reducing front apron and smooth underbody. The 'Air Curtains' in the front bumper also work to cool the brakes before exiting through the M gills behind the front wheels, ensuring air turbulence is kept to a minimum.

This MMA fighter has also gone on a diet, dropping 60kg compared to its predecessor despite being a larger car overall. Chief amongst the weight saving measures is the extensive use of aluminium for not only the chassis but also the bonnet and front wings. Carbon-Fibre Reinforced Plastic (CFRP) has also been used for parts like the drive shaft and front suspension strut brace.

Interior

Seating in the M4 Convertible is purely for four with front occupants getting electrically adjustable leather sports seats. Those in the rear also enjoy individual thrones. Bespoke 'M' trim covers the interior from the three-spoke steering wheel to the unique, white backed instruments and from the gear lever to the driver's footrest.

Mechanicals

The engine in the M4 Convertible is a veritable Smorgasbord of BMW's best work: 3.0-litre straight-six engine? Check. TwinPower turbo technology in the guise of two turbochargers? Check. Valvetronic and Double Vanos? Check and check. The result is an engine that is said to crave the redline in the way the naturally aspirated V8 that came before it did while offering up peak power of 431hp (produced between 5,500- and 7,300rpm) and 550Nm of torque (on tap from 1,850- to 5,500rpm). With the standard six-speed manual transmission this means a 0-62mph time of 4.6 seconds and the optional seven-speed M Double Clutch Transmission (M DCT) shaves 0.2 seconds off that.

Whatever the gearbox, top speed is limited to 155mph and the new car delivers fuel economy of 31mpg (32.5mpg for the auto) with emissions of 213g/km (203g/km for auto). Though we doubt anyone in the market for a car such as this will be too concerned with these figures. Of more import is the fact that the fancy CFRP drive shaft leads to an updated version of the Active M differential, which can shuffle power along the rear axle in a fraction of a second, and that the exhaust system features electronically controlled flaps that "help create an unmistakable BMW M sound."

Anything else?

Naturally, being an open car, getting the roof off the M4 Convertible is of paramount importance. Thankfully, at speeds of up to 11mph this action is completed in 20 seconds with the simple flick of a button, and the tri-fold roof stows away into the boot. Roof open the luggage capacity is 220 litres or 370 litres with it closed. Protected from the elements the M4 Convertible is said to be 2dB quieter than its M3 Convertible predecessor thanks to the 'noise absorbing' headliner.

Paul Healy - 3 Apr 2014