It’s only March, yet it's been a very busy year for BMW.Locally, Wheels24 editor LES STEPHENSON attended the 2 and 4 series convertible model launches earlier in March. However, South Africans are eagerly awaiting the arrival of the M3 sedan and M4 coupe due later in 2014, July and October respectively.The automaker recently revealed the M3 Saloon and M4 Coupe derivatives at the 2014 Detroit auto show. Now, details of the M4 Convertible are out for the fifth-generation high-performance open-top car. IMAGE GALLERY: BMW M4 Convertible Powered by the same in-line six-cylinder engine as the M3 Saloon and M4 Coupe, the Convertible is available in either an optional six-speed manual or seven-speed M Double Clutch transmission. It kicks out 321kW/550Nm and reaches 100km/h in 4.6sec (4.4 for auto) with a limited top speed of 250km/h. It has a claimed combined fuel consumption of 9.1 litres/100km and 8.7 for the auto; CO2 emissions are rated at 213 and 203g/km. BMW says these figures are achieved by advanced, race-derived technologies, including special cooling systems. The automaker said: “An indirect intercooler maximises charge pressure and engine output, while the main radiator is supplemented by other coolers located in the sides of the engine bay for the high and low-temperature water circuits as well as for the engine and transmission oil (with the M DCT gearbox). "An additional electric coolant pump helps to cool the turbocharger bearing mounts when the car comes to rest." Then there’s a lightweight magnesium sump with a special cover to minimise the movement of oil during high g-force cornering, and an additional pump and sophisticated oil return system maintain stable oil circulation under hard acceleration and braking. The exhaust system has electronically controlled flaps which minimise back-pressure and ensure that the M4 Convertible has an unmistakable BMW M sound. The optional seven-speed M double-clutch transmission combines two gearboxes, each with its own clutch. Shifts are therefore completed with no interference to the power delivery, enhancing both performance and efficiency. Gear shifting can be fully automatic or via the selector lever or steering column-mounted paddles. MORE EFFICIENCY, BETTER PERFORMANCEThe automaker also says the M4 Convertible is 60kg lighter than the outgoing M3 Convertible it replaces, now weighing 1750kg.Efficiency comes from the dynamically shaped front apron, smooth underbody and special airflow channelling through the front end while the aero curtains and M side gills with air breathers behind the front wheels assist in reducing drag. Even the twin-stalk door mirrors are designed to help the car cut through the air better.It’s fitted as standard with M compound brakes for maximum stopping power, fade resistance and low weight. Other standard items include the Active M differential to enhance traction and directional stability and an electronically controlled multi-plate limited slip differential linked to the dynamic stability control system.The DSC system includes anti-lock brakes and M Dynamic Mode. Other standard stability support features include cornering brake control, dynamic brake control, brake drying and hill-start assistant. In the UK, it will also be fitted as standard with Adaptive M suspension with comfort, sport and sport+ modes.USUAL M STUFFDistinctive M design goodies, says BMW, include a power dome in the bonnet, a sculpted front apron with three air intakes and a black double-slat kidney grille. Standard 19” M double-spoke light alloy rims in the UK, flared front and rear wheel arches, M side gills and quad exhaust tailpipes.The three-part metal roof now provides significantly improved noise insulation – up to 2dB quieter – thanks to the new headlining and takes only 20 seconds to go down, or up, at up to 12km/h. There’s a new, wider wind deflector and three-stage neck-warming Air Collar in the front seats available optionally; the rear seats’ roll-over hoops are now neatly hidden behind the headrests. Boot space is rated at 370 litres when the roof is closed and 220 litres when it is stowed.Inside the car there are electrically adjustable, heatable M leather seats with illuminated logos; an M steering wheel, chromed trim and three-colour M stitching. The BMW M4 Convertible will be offered with an extensive specification in the UK. Standard equipment, in addition to Adaptive M suspension and 19” M light alloy wheels, will include the BMW Professional media package, upgraded Bluetooth and USB, front and rear park distance control, folding mirrors and heatable front seats. The M4 Convertible will go on sale in the UK on September 6 at the equivalent of about R1.1-million.BMW South Africa says the M4 Convertible will arrive in SA in October 2014 and pricing has not yet been finalised.