BMW M4 Convertible (2015)

Technology: Innovative measures across the board deliver maximum performance, precision and agility

In keeping with the philosophy of BMW M GmbH, the development of the new BMW M4 Convertible has reflected an unwavering commitment to outstanding driving dynamics combined with uninhibited everyday usability. Indeed, the M4 Convertible is powered by the same 317 kW/431 hp sixcylinder in-line engine with M TwinPower Turbo technology found in the new M3 Sedan and new M4 Coupe. The aerodynamics of the open-top sports car have been optimised to deliver ultra-dynamic handling properties and maximum efficiency, with extensive intelligent lightweight design measures also forming part of its make-up.

High-revving straight-six engine with M TwinPower Turbo technology

With maximum output of 317 kW/431 hp available between 5,500 rpm and 7,300 rpm and peak torque of 550 Newton metres (406 lb-ft) on tap over an extremely broad rev band (1,850 rpm - 5,500 rpm), the BMW M4 Convertible's six-cylinder engine has the firepower to provide elite sports car levels of performance. Fitted with the standard six-speed manual gearbox, it needs just 4.6 seconds for the sprint from 0 to 100 km/h (62 mph), dropping to 4.4 seconds if the optional seven-speed M Double Clutch Transmission is specified. Top speed is an electronically governed 250 km/h (155 mph). The M TwinPower Turbo engine hits maximum revs of 7,600 rpm and combines superior sporting ability with outstanding efficiency. Indeed, the BMW M4 Convertible posts fuel consumption of just 9.1 litres per 100 km / 31 mpg imp (M DCT: 8.7 l/100 km / 32.5 mpg imp) in the EU cycle - equating to CO2 emissions of 213 g/km (203 g/km) - and already meets the EU6 exhaust gas standard.

Technology straight off the race track delivers unbeatable performance

With its engine generating such impressive performance, it's little surprise to find that the other links in the BMW M4 Convertible powertrain are also fully track-ready. In order to ensure optimum operating temperatures in everyday use, on short journeys around town and out on the race track, the six-cylinder unit has an immensely effective cooling system. This includes an indirect intercooler to maximise charge pressure and engine output. As well as a main radiator, the track-ready cooling concept also comprises water coolers repositioned to the sides for the high and low-temperature water circuits as well as for the engine and transmission oil (if the M Double Clutch Transmission is specified). An additional electric coolant pump cools the turbocharger bearing mounts when the car is stationary.

The vast experience of BMW M GmbH in motor sport is also evident in the engine's oil supply system. At its core is a low-weight magnesium oil sump with a special cover to minimise movement of the oil under the impact of strong dynamic lateral acceleration. An additional oil extraction pump and a sophisticated oil return system situated close to the turbocharger likewise help to maintain stable oil circulation under extreme acceleration and deceleration.

An engine sound in keeping with the car's motor sport genes is provided by an innovative flap arrangement in the twin-pipe exhaust system. The electrically controlled flaps just before the rear silencer minimise exhaust back-pressure and help create an unmistakable BMW M sound.

Intelligent lightweight design across all areas of the car

As well as outstanding dynamic qualities, intelligent lightweight design also allows the BMW M4 Convertible to claim exemplary efficiency. Its extensive weight-saving measures produce a DIN kerb weight of just 1,750 kilograms - around 60 kilos less than its predecessor.

Among the key contributors here are the aluminium front side panels and bonnet, with lightweight aluminium construction also a feature of the chassis. Extensive use is also made of a material that is both lightweight and extremely stiff, and therefore durable: carbon-fibre-reinforced plastic (CFRP). The propeller shaft is one of the elements of the BMW M4 Convertible made from CFRP, which permits a single-piece construction. This leads to weight savings of 40 per cent over the previous model and therefore a reduction in rotating masses, which in turn results in more dynamic powertrain response.

Also made from CFRP is the precision strut in the engine compartment, which weighs only 1.5 kilograms yet offers rigidity beyond that of a comparable aluminium component. It therefore plays a key part in the car's excellent steering response and precision.

Active M Differential, Electric Power Steering and M compound brakes ensure precise, extremely dynamic handling

The Active M Differential fitted to the driven rear axle of the BMW M4 Convertible enhances traction and directional stability with the help of an electronically controlled multi-plate limited-slip differential. Its control unit links up with the DSC (Dynamic Stability Control) system and also takes into account the position of the accelerator pedal, the rotational speed of the wheels and the car's yaw rate. The degree of lock on the rear axle - which may be anywhere between 0 and 100 per cent - is adjusted as required within a fraction of a second. Optimising traction in this way also provides unbeatable driving stability in challenging conditions and allows impressively dynamic acceleration out of corners.

The electromechanical steering system offers the twin gifts of a direct steering feeling and precise feedback. With the integrated Servotronic function the level of steering assistance is automatically adjusted according to the car's speed. The steering also offers the driver three settings as standard, which can be selected at the touch of a button. COMFORT, SPORT and SPORT+ modes allow the driver to adapt the level of steering assistance to suit the situation at hand and the driver's personal tastes.

The M4 Convertible is fitted as standard with BMW M compound brakes, which boast impressive feel, outstanding stopping power and high resistance to fade - in addition to their low weight.

Flawlessly interlinked aerodynamics measures

The sophisticated aerodynamics of the BMW M4 Convertible play a standout role in imbuing the car with its unbeatable performance and efficiency. For example, lift-reducing measures such as the powerfully formed front apron, airflow channelling through the front end and a smooth underbody help give the car outstanding handling properties. Furthermore, elements like the Air Curtains and M gills with integrated Air Breathers rearwards of the front wheels minimise turbulence in the front wheel arches. Together with the aerodynamically optimised exterior mirrors in twin-stalk style, these are also highly distinctive design features of the BMW M3/M4 line-up.

The BMW M4 Convertible's three-part folding metal hardtop offers significantly improved sound insulation over its predecessor thanks to its "noise-absorbing" headliner, which reduces wind noise by up to 2 dB compared with the outgoing model. In addition to this appreciable increase in comfort, the fully lined roof also offers full winter usability. One press of a button and the dynamic, closed-roof high-performance sports car transforms into a sporty and elegant open-top machine in a shade over 20 seconds. And the roof can even be lowered while on the move, at speeds of up to 18 km/h (11 mph).

The revised and wider-sided optional wind deflector and new, likewise optional neck warmer - which is adjustable through three stages - ensure the driver and passengers can also enjoy a relaxing open-top drive at low temperatures and at higher speeds. The standard loading assistance system, meanwhile, raises the folded roof when stowed away in the rear to allow easy access to items in the boot. Load capacity is 220 litres with the roof open or 370 litres when the hardtop is closed.

Design: An aesthetically persuasive combination of dynamics and elegance

The new BMW M4 Convertible shares the sporty, dynamic looks of the BMW 4 Series Convertible on which it is based, but employs M-specific M design elements to underline its outstanding performance and lend it an unmistakable appearance.

Exterior design shines the spotlight on superior performance

The new BMW M4 Convertible is larger than its predecessor in terms of width, wheelbase and track width, and boasts perfectly balanced proportions. Its long bonnet, short front and rear overhangs, and set-back passenger compartment are all key contributors to the car's hallmark BMW lines. When closed, the three-part folding metal hardtop seals a harmonious yet dynamic coupe form, unruffled by B-pillars. When the roof is open, the side view of the BMW M4 Convertible displays a zesty elegance and is encumbered by neither the rollover protection system - now hidden away fully from view behind the rear head restraints - nor aerials (e.g. for the radio).

Standout M design features include the hallmark power dome on the bonnet, BMW M double-spoke wheels, eye-catching exterior mirrors in twin-stalk style, M gills with integrated Air Breathers rearwards of the front wheel housing, flared front and rear wheel arches, and the high-gloss polished, slanting pair of twin exhaust tailpipes.

Dynamic character continues seamlessly through the interior

The new BMW M4 Convertible's interior likewise leaves little doubt as to its family links with the high-performance M3 Sedan and M4 Coupe. For example, a host of now customary BMW M equipment details heighten the car's elevated sporting pretensions. These include M-specific circular instruments with white graphics, the M leather steering wheel with chrome trim and colour contrast stitching, an M gearshift lever, M door sill finishers and an M driver's footrest.

As standard, the driver and front passenger enjoy the services of electrically adjustable, heavily contoured leather sports seats with recessed head restraints and integral belt guides. A special stylistic highlight of the M4 Convertible's front seats is the illuminated BMW M logo integrated into the head restraints. The two individual rear seats likewise offer impressive comfort and lateral support, thanks to clearly defined seat surfaces and backrests.

BMW Individual: Unlimited scope for meeting customer desires in terms of exclusivity and individuality

The BMW M4 Convertible sets its sights primarily on those customers for whom - in addition to performance - a car's looks, the allure of exclusivity and, not least, the luxury of open-top driving play an important role. These customers are particularly keen to ensure their car has a stylish and distinctive appearance. Extending beyond the standard and optional equipment details available for the BMW M4 Convertible, the rich variety of BMW Individual allows virtually limitless scope when it comes to adapting the car in detail to owners' personal visions of comfort, luxury and style.

Over 20 years of experience in the individualisation of BMW models

What began in the early 1990s with the creation of sensational one-offs for the likes of Karl Lagerfeld and José Carreras has, under the BMW Individual umbrella, developed into a one-of-a-kind department for the personalisation of BMW models. The BMW Individual range comprises two areas: the BMW Individual Collection and the BMW Individual Manufactory.

The BMW Individual Collection offers a unique driving experience of the highest order. Special colours and materials can be matched precisely to customers' desires, resulting in a car very much in their own image. The BMW Individual features for M Automobiles include exclusive interior trim elements and extremely high-class Merino leather upholstery variants. Similarly oozing exclusivity is the range of available exterior paint finishes. Customers are presented with a collection of ultra-radiant metallic colours and four sporty, matt Frozen metallic shades.

The BMW Individual Manufactory is not so much a place as an idea, which is turned into tangible form on a daily basis. That idea is total customer orientation. Here, special requests from BMW customers that go beyond the BMW Individual Collection take shape. Whether it is elaborate paintwork, unconventional materials or outré requests, the BMW Individual Manufactory draws on its experience and craftsmanship to make every vision of exclusivity a reality - provided it does not conflict with safety standards, the brand character or legal requirements. The Manufactory also develops and completes special editions, show cars and special market-specific model series.

Metallic or matt: the BMW Individual paint finishes

A BMW M4 Convertible with BMW Individual refinements can be identified at a glance by its standout exterior paintwork alone. Customers can choose from brilliant metallic tones and the softly shimmering matt finish of Frozen metallic shades. All the exterior paintwork options available from BMW Individual showcase the dynamic and eye-catching design language of the BMW M4 Convertible with a particular allure and extra impact.

A BMW Individual metallic paint finish possesses an unusual brilliance. Its special pigmentation means that the paint colour shifts depending on the incidence of light, lending the surfaces a striking depth. Tanzanite Blue metallic is a fine example. Similarly to the precious mineral from which it takes its name, this unique BMW Individual paint finish switches between a radiant turquoise and a serene dark blue according to the incidence of light and the angle from which it is viewed.

Numerous options when it comes to interior decoration

BMW Individual has for many years now used only the most exclusive leather available for a BMW: naturally very soft and fine, BMW Individual fine-grain Merino leather boasts a unique and exclusive look and feel. The colours of the leather appointments and leather-covered instrument panel likewise set a new benchmark. The nine specially developed colour shades range from expressive to classically elegant and, like BMW Individual leather trim with contrast stitching, are available exclusively through BMW Individual.

BMW Individual interior trim strips lend a highly effective touch to this cabin ambience, rare precious woods creating exclusive highlights within the BMW M4 Convertible's interior.

Equipment: Generous standard equipment supplemented by numerous options for enhanced dynamics and comfort

The new BMW M4 Convertible is delivered from the factory with a specification in keeping with its dynamic and luxurious nature. Customers can additionally choose from an extensive range of equipment options, which allow the character of the open-top sports machine to be honed for even sharper dynamics or further enhanced comfort.

Exterior and interior equipment underlines the car's impressive performance potential

The BMW M4 Convertible is immediately recognisable as a high-performance model from BMW M GmbH thanks to its signature design elements, such as a lightweight bonnet with eye-catching power dome, sculpted front apron with three large air intakes, black double-bar kidney grille, exterior mirror casings in twin-stalk style, rear apron with integrated diffuser, and an exhaust system with four tailpipes. Customers can further strengthen the confident appearance of their car with a broad range of exterior paint shades, including ultra-exclusive BMW Individual finishes.

The BMW M4 Convertible comes as standard with low-weight, forged 18- inch BMW M light-alloy wheels (front axle: 9 J x 18, rear axle: 10 J x 18) with mixed tyres (front axle: 255 mm, rear axle: 275 mm). Available as an option are forged 19-inch M light-alloy wheels in either Ferric Grey or Black (front axle: 9 J x 19, rear axle: 10 J x 19) with mixed tyres (front axle: 255 mm, rear axle: 275 mm).

Inside the car, customers can select from among four exclusive colours for the standard fine-grain Merino leather upholstery. Beyond this, the BMW Individual range offers nine further colour options for a personal touch. The sporty and dynamic character of the interior is the product of striking standard equipment details like the M double-spoke leather steering wheel, which sports an M logo, chrome trim and colour contrast stitching.

Innovative technologies delivering top-level performance

Power transfer in the BMW M4 Convertible is via a six-speed manual gearbox as standard. Available as an option is the seven-speed Double Clutch Transmission M DCT, which allows the driver to change gear not only using the selector lever in the centre console but also via the shift paddles on the steering wheel. This transmission effectively combines two gearboxes, each with its own clutch. This means gear changes are executed with no interruption in the flow of power - and the shift processes are therefore shorter. Drivelogic allows the driver to select from different shift modes, which see the M4 Convertible adopting a particularly comfort-oriented, economyfocused or ultra-sporty approach to gear changes when in automatic mode. The Launch Control function also integrated into M DCT enables optimum acceleration off the line.

The standard Active M Differential optimises traction at the rear axle. The electromechanical steering system, meanwhile, represents a new development from BMW M GmbH and is the critical component in the link between driver and car. It offers the gifts of direct steering feel and precise feedback. The integrated Servotronic function electronically adjusts the level of steering assistance according to the car's speed, providing optimum steering characteristics at all speeds. Three steering settings (COMFORT, SPORT and SPORT+) can be selected at the touch of a button to adjust the level of steering assistance to the situation at hand and to the driver's personal tastes.

The optional Adaptive M suspension likewise comes with COMFORT, SPORT and SPORT+ modes. The BMW M4 Convertible is equipped as standard with M compound brakes, but customers can also order their car with even lighter and more effective M carbon ceramic brakes, which boast the additional visual highlight of gold-painted callipers.

Optional equipment items provide comprehensive driver information

Needless to say, the BMW M4 Convertible is also available with the wide range of driver assistance systems and mobility services introduced under the BMW ConnectedDrive banner, some of which are already familiar from the BMW M3 Sedan and BMW M4 Coupe. Among the highlights are the new generation of the Navigation system Professional offering extra capability, sharper graphics and 3D elements for the map display, Driving Assistant Plus, which warns the driver of a looming collision with a pedestrian or vehicle, the intelligent anti-dazzle LED High Beam Assistant, and Active Protection with Attention Assistant.

The optional Head-Up Display comes with additional, M-specific functions such as a gear display, rev counter and Optimum Shift Indicator.

Hall of fame: A byword for open-top driving pleasure for over a quarter of a century

The new BMW M4 Convertible builds on 26 years of tradition. Indeed, a Convertible has lined up alongside its two-door Coupe sibling as a firm fixture of the BMW M3 in all four generations.

First generation: the racing car with the soft-top

The launch of the first BMW M3 in 1986 served primarily to satisfy the homologation requirements for what was then the German Touring Car Championship (DTM). In order to take its place on the grid for this prestigious race series, BMW had to come up with a series-produced version of the competition car and build 5,000 examples of it for sale within a year. The road-spec BMW M3 was created with the demands of motor sport very much at centre stage and there were no plans initially for an open-top version. However, after around two years of resistance, BMW eventually gave in to significant customer demand, and the BMW M3 Convertible was unveiled in 1988. It was based on the four-seater BMW 3 Series Convertible and powered by a four-cylinder petrol engine initially producing 143 kW/195 hp. In 1990, output was increased to 158 kW/215 hp, enabling the open-top M3 to accelerate to a top speed of 239 km/h (148 mph) - making it the world's fastest four-seater series-produced convertible at the time.

Second generation: new advances in safety technology

The powers that be in BMW's motor sport department - now rechristened M GmbH - had planned an additional Convertible version of the secondgeneration BMW M3 (launched in 1992) from the outset. Based on the fourseater 3 Series Convertible, the BMW M3 Convertible was launched in 1994 with a raft of innovative safety technology on board. For example, the rollover bars of the standard rollover protection system - positioned behind the rear seat head restraints - would spring up in an instant if the car was in danger of turning over, teaming up with the ultra-rigid windscreen frame to protect the passenger compartment. The BMW M3 Convertible was just 80 kilograms heavier than the Coupe variant, but delivered a comparably high level of performance. The 210 kW/286 hp model needed 6.2 seconds for the sprint from 0 to 100 km/h (62 mph), just 0.2 seconds more than the Coupe. And once its output had been boosted to 236 kW/321 hp in 1995, the Convertible reduced its figures to an even more impressive 5.6 seconds (Coupe: 5.5 s). Top speed remained unchanged at an electronically governed 250 km/h (155 mph).

Third generation: shining an even brighter spotlight on the car's sporting character

In spring 2001, almost exactly a year after the starting gun had been fired on the third generation of the BMW M3, M GmbH unveiled the Convertible variant to join its Coupe stablemate in the line-up. It was identical to the M3 Coupe up to the A-pillar, but a striking beltline gave the open-top model an even broader, more powerful appearance. The BMW M3 Convertible therefore cut a more muscular, broader, more hunkered-down figure than any BMW M3 before it. And it had the bite to back up the bark; hallmark M attributes such as a 252 kW/343 hp high-revving naturally-aspirated engine, beautifully tuned M suspension, a variable M differential lock and M highperformance brakes enshrined the BMW M3 Convertible as an elite athlete of its kind. The sprint from rest to 100 km/h (62 mph) took just 5.5 seconds.

Fourth generation: giving the sporting character an even sharper edge

Less than a year on from the debut of the fourth-generation BMW M3 Coupe and the four-door Sedan that followed a little later, BMW stirred the fires of anticipation among open-air driving enthusiasts with the launch of the BMW M3 Convertible in spring 2008. A 4.0-litre eight-cylinder engine generating 309 kW/420 hp - and sustaining around 85 per cent of its 400 Newton metre (295 lb-ft) peak torque across a rev range of 6,500 rpm - gave drivers of the drop-top four-seater an impressive armoury with which to sate their appetite for sporty, dynamic corner-chasing and relaxed cruising alike.