The new BMW 4 Series Convertible is the latest entrant to a market segment where BMW has enjoyed widespread acclaim and great success over five generations of premium Convertibles.

The design language introduced with the 4 Series Coupé is evident in this, the second model debut in the series. The result is a sporting yet elegant car, roof raised or lowered, that is clearly distinguished from its 3 Series brethren. It’s a lower, wider, longer car than the old 3 Series Convertible, with a visibly greater sporting intent.

The BMW 4 Series Convertible has a folding metal roof which can be raised or lowered in just 20 seconds and at speeds of up to 8mph. The optional wind deflector can now be stored behind the seats when not in use, and a new Air Collar system blows warm air around the necks of front seat occupants for open-air driving on cooler days.

At launch the 4 Series Convertible range will consist of two petrol engines and one diesel engine choice, available across five different trim levels. The range is characterised by a marked increase in the standard equipment level offered, despite the minimal increase in price.

The BMW 4 Series Convertible goes on sale 8 March 2014.

Model Powerhp TorqueNm 0 – 62mph Seconds Top Speed mph Combined mpg CO 2 Emissions g/km BMW 435i Luxury Convertible 306 400 5.6 (5.5) 155* 34.9 (37.7) 190 (176) BMW 428i SE Convertible 245 350 6.4 (6.4) 155* 41.5 (42.8) 159 (154) BMW 420d SE Convertible 184 380 8.2 (8.2) 146 55.4 (58.9) 133 (127)

*electronically limited

Design: an elegant, sporting exterior and interior

Traditionally, BMW Convertibles have dynamic and balanced proportions – when the roof is up or down – and the new BMW 4 Series Convertible is no exception.

The dimensions of the new car differ significantly from the outgoing BMW 3 Series Convertible. The overall length of 4,638mm has been extended by 26mm; the wheelbase has grown by 50mm and, together with the wider front track, this gives the car a very athletic stance on the road. The shorter overhangs, long bonnet and set back passenger compartment further accent the graceful silhouette.

Although the BMW 4 Series Convertible is a more overtly sporting car than its predecessor, the design of the front end reflects its close family ties with the kidney grille and twin headlights showing it‘s unmistakably a BMW. The optional adaptive full-LED twin headlights, with their hexagonal design, combine with the slightly forward-slanting BMW kidney grille to form a strong stylistic statement. The width of the vehicle is accentuated by a large air intake in the front apron below the headlight line. On the far left and right-hand edges of the air intake are the additional, aerodynamically refined, Aero Curtains.

From the side, the sloping roofline stretches the car’s overall appearance and elegantly accentuates the sporting profile. The moulding at the juncture of the three-piece folding hardtop and the body is available in chrome, black or satin aluminium, depending on the model variant. The shallow side windows, signature BMW Hofmeister kink and the double shoulder line teams up with the striking door sill line, to give the car a dynamic elegance. With the top lowered, the smooth, flowing silhouette is not compromised by radio antennas or rollover bars, which are hidden behind the rear head restraints.

Located behind the BMW 4 Series Convertible’s front wheels are Air Breathers designed to reduce drag around the wheel arches. The sporting character extends into the design of the rear where prominent horizontal lines and broadly stretched L-shaped tail lights, positioned at the outer edges, draw attention to the muscular wheel arches and wide track.

Three-piece retractable hard-top: form and function

The three-piece metal roof of the new BMW 4 Series Convertible means that occupants can enjoy a warm, quiet, snug cockpit whatever the weather outside. A simple push of a button transforms the dynamic coupé into an elegant convertible in just 20 seconds and can now be lowered when the vehicle is travelling at speeds of up 8mph.

The hard-top of the BMW 4 Series Convertible features a number of design improvements to reduce noise levels for a much quieter interior ambience. In addition, the sound-absorbing headliner also reduces wind noise by up to 2dB.

The redesigned optional wind deflector is now wider at the sides, and the optional three-temperature Air Collar allows for comfortable open-air driving at low temperatures. The wind deflector is now smaller, lighter, more effective and easier to use. When it is not needed, it can be stored behind the rear seats to save space.

The BMW 4 Series Convertible also has plenty of space in the boot, even when the retractable hard-top is lowered. The new Convertible offers wider access to the luggage compartment, and an electro-hydraulic loading assistance system pivots and positions the folded hard top to ensure maximum utilisation of the 220litres of storage space. When the top is up the luggage compartment has a volume of 370 litres, 20 litres more than in the BMW 3 Series Convertible. Moreover, with the optional Through-loading system a flat and level storage area can be utilised when the backrest of the rear bench seat is folded down.

The interior: wrap around cockpit; boat deck rear

The interior of the BMW 4 Series Convertible blends sporting intent and exclusivity. All of the controls are arranged ergonomically around the driver to provide optimum access to all functions. A sports steering wheel, circular instruments in black panel look and the freestanding flat screen iDrive monitor, controlled by the iDrive Touch Controller when the Professional Media package is specified, epitomise this functional elegance. The completely new design of the front seats includes integrated retractable seat belts , unique in this class, as well as being electrically adjustable as standard. Dakota leather upholstery with Sun Reflective technology is standard on all models.

In the rear, the bench design is contoured to form two individual seats, with cup holders and a storage tray for small items between them. The rear head restraints are separated from the concealed rollover bars and can be removed if desired. The effective rollover bars are comprised of two steel elements hidden behind the rear seats whereby in critical situations, sensors trigger the system and the rollover bars are extended within less than 200ms.

High level of standard specification

The new BMW 4 Series Convertible will offer a significantly higher standard specification that the model it replaces. As standard the 4 Series is fitted with front and rear parking sensors, heated electric front seats, Servotronic steering, a Sport-multi-function leather steering wheel and Xenon headlights. DAB radio, Dakota leather upholstery with SunReflective technology, Two-zone air conditioning, Cruise control, Bluetooth, USB, Comfort Go, Drive Performance Control, iDrive Controller and 6.5-inch colour screen complete the standard specification of all models across the range.

Five individual model trims: the BMW 4 Series Convertible personalised

There are five different trim levels for the new BMW 4 Series Convertible. The standard SE trim level can be built upon with the Sport, Modern, Luxury and M Sport trims, which all embody different takes on the car’s character and offer 18-inch alloy wheels and sports seats as standard.

The Sport model features a high-gloss black finish for exterior body elements in the front and rear bumpers and the kidney grille slats. Inside the car, contrasting black and red accents provide a sporting ambience with red contrast stitching on the sports steering wheel and the red trim rings in the inner circle of the instrument dials.

With the Modern model, matt chrome and satin highlight the exterior details and trim. Inside, the light-coloured dashboard, coupled with a steering wheel in dark oyster (both also available in black), creates an airy feel to the cabin. Leather upholstery in oyster or black, and a choice of four trim surfaces with accent strips in Pearl Gloss Chrome, adds to contrast of materials, while door panels in two-tone colours are available.

The Luxury model has all the exterior details in chrome, while the same finish is also used in the interior, including the frame surrounding the audio and air conditioning system. High-gloss wood strips, leather seats with contrast stitching and a choice of two upholstery variants in four classically elegant colours complete the look. The Business Media Package also comes as standard on Luxury models.

The M Sport model is available for those looking to put the emphasis firmly on sportiness. The aerodynamic package includes numerous body components such as the front apron with large air intake, the rear bumper with diffuser and the eye-catching side skirts. Other features include the BMW Individual High-gloss Shadow line trim and the exclusive optional exterior paint Estoril Blue metallic; 18-inch or optional 19-inch light-alloy wheels are in the hallmark M design. Inside the car M doorsill finishers, an M leather steering wheel and Business Media Package are standard, while the driver and front passenger also have exclusive sport seats with M piping and royal blue contrast stitching. M Sport suspension is also included while the M Sport braking system with contrasting blue calipers is now optionally available.

The chassis: finely tuned dynamics for comfort and driving pleasure

The new BMW 4 Series Convertible offers an engaging, dynamic yet comfortable driving experience whether the roof is up or down. It displays an immediate road presence with its longer wheelbase and wider track – 1,545mm at the front and 1,594mm at the rear. The BMW 4 Series Convertible also sits 10mm closer to the road surface than the latest BMW 3 Series Saloon, helping to bring the car’s centre of gravity down.

The chassis of the new BMW 4 Series Convertible is based on that of the new BMW 4 Series Coupé. However the springs, damping and axle characteristics have all been tailored precisely for the new convertible. The chassis engineers have made improvements to the agility and accuracy offered by the chassis thanks to the modification and fine-tuning of variables such as the camber angle, the track and the roll centre.

The front axle and suspension makes good use of aluminium to save weight, such as in the spring struts, wishbones and swivel bearings, which provide a substantial reduction in unsprung masses. Adjusting the position of the control arms from their arrangement on the latest BMW 3 Series Saloon gives the car a 19mm lower roll centre, making it more dynamic. At the rear, the car uses BMW’s proven five-link axle, and its characteristics have been tuned specially for the BMW 4 Series Convertible. In addition, extra-wide mounts and supports on the wheel carriers for track and camber, slightly repositioned pivot points, ultra-stiff control arms and axle subframes, and the use of thrust arms to connect the suspension with the body all provide an excellent basis for a sporting set-up that doesn’t neglect driver comfort.

Servotronic power steering is standard, however Variable Sports Steering is optionally available. In keeping with its dynamic performance capability, the new BMW 4 Series Convertible comes equipped with powerful swing-calliper or fixed-calliper brakes and large, inner-vented brake discs. The callipers on the front axle are made from aluminium, which as well as contributing to low unsprung masses means superior heat tolerance, excellent wet braking performance, ease of use and excellent feel. A brake pad wear indicator and the Brake Drying function are standard on all models.

The body: intelligent lightweight design

The new BMW 4 Series Convertible’s intelligent lightweight construction concept makes a major contribution to the car’s dynamic qualities. The use of high- and ultra-high-strength multi-phase steels maximises the body’s strength. The torsional rigidity has been increased by 40 per cent compared with the predecessor model. Nevertheless, most BMW 4 Series Convertible variants are up to 20kg lighter than their predecessors, even though the new vehicle is larger and complies with more stringent safety standards.

When the hardtop is up, the new BMW 4 Series Convertible has an identical drag coefficient to the new BMW 4 Series Coupe, thanks to the optimisation of the front apron and the rear body design. The BMW Aero Curtains in the front apron generate a veil of air that reduces turbulence around the front wheels, while the new Air Breathers divert some of the air flowing through the wheel arches, thereby reducing air resistance. All these innovations serve to optimise fuel economy and improve high-speed stability.

M Sport suspension and brakes; Adaptive suspension

The M Sport suspension included on M Sport models can also be ordered separately, enhancing the dynamic handling characteristics of all variants in the model range. It consists of a firmer spring/damper set-up, stiffer anti-roll bars and tweaked suspension settings to suit the new BMW 4 Series Convertible. BMW also offers the M Sport braking system, which features aluminium fixed callipers (four-piston at the front, two-piston at the rear) and generously sized discs for extremely low weight and very short stopping distances.

Alternatively, there is the Adaptive M Sport Suspension option which adjusts the damper mapping to the road surface and driving situation at any given moment. The driver can also use the Drive Performance Control switch to vary the basic suspension settings between the more comfortable and the sportier ends of the scale. The switch – located on the centre console – has four modes: ECO PRO, COMFORT, SPORT or SPORT+ (in conjunction with the Sport or M Sport trim).

Powertrain: TwinPower technology for performance and efficiency

The state-of-the-art powertrain technology under the skin of the new BMW 4 Series Convertible ensures it delivers an engaging yet efficient driving experience. As is the BMW custom, the engines are in-line and longitudinally mounted up front, sending their power to the rear wheels. All use BMW’s TwinPower Turbo technology, which combines sporty performance characteristics with exceptional efficiency, and are all EU6 compliant.

The new BMW 435i Convertible heads up the range with its straight-six petrol engine with instantaneous power delivery, refinement and efficiency. Equipped with High Precision Direct Injection and Valvetronic fully variable valve control, the 3.0-litre engine with an aluminium crankcase develops a maximum output of 306hp between 5,800 and 6,000rpm, and peak torque of 400Nm is generated from as low as 1,200rpm through to 5,000rpm. The new BMW 435i Convertible can sprint from zero to 62mph in just 5.6 seconds, on the way to an electronically limited top speed of 155mph. Even so, the average fuel consumption is from 34.9mpg and CO 2 emissions from 190g/km. The car is even more economical when fitted with the optional eight-speed Sport automatic gearbox, achieving a combined fuel consumption of just 37.7mpg, while CO 2 emissions are down to 176g/km.

The new BMW 428i Convertible is defined by the spirited power delivery, impressive torque, high maximum revs and low weight of its 2.0-litre four-cylinder turbocharged engine. As much as 245hp is produced from 5,000–6,500rpm, and peak torque of 350Nm is available between 1,250-4,800rpm. This equates to a zero to 62mph dash in 6.4 seconds and an electronically limited top speed of 155mph, while the average fuel consumption stands at just 41.5mpg, and CO2 emissions are only 159g/km. The optional eight-speed Sport automatic gearbox also opens up further potential for fuel savings: combined fuel consumption of 42.8mpg and CO2 emissions of just 154g/km.

The diesel engine choice at launch is the new BMW 420d Convertible. It uses the latest-generation four-cylinder diesel engine with composite aluminium crankcase, latest-generation common-rail direct injection technology, a turbocharger with variable turbine geometry and precise solenoid valve injectors, ensuring instantaneous throttle response with extremely low fuel consumption and emissions. With a maximum output of 184hp at 4,000rpm and peak torque reaching 380Nm between 1,750-2,750rpm, it’s no surprise the car can sprint from zero to 62mph in just 8.2 seconds and accelerate up to 146mph if required. Average fuel consumption stands at 55.4mpg and CO 2 emissions of 133g/km. With the optional eight-speed Sport automatic gearbox combined fuel comsumption falls to 58.9mpg and CO 2 emissions to 127g/km.

A six-speed manual gearbox is standard in the new BMW 4 Series Convertible. Alternatively, customers can specify an eight-speed automatic gearbox that adjusts to a wide range of driving styles and offers manual gear changes via paddles on the steering wheel.

EfficientDynamics: saving fuel the intelligent way

Thanks to BMW’s EfficientDynamics technologies the BMW 4 Series Convertible combines outstanding economy with trademark driving pleasure.Efficient petrol and diesel engines, with lightweight and innovative transmissions with reduced frictional losses, contribute to fuel savings and low emissions. Other features that improve overall economy include lightweight construction, intelligent aerodynamics, on-demand power for ancillary units and an innovative Proactive Driving Assistant that tells the driver when to ease off the accelerator upon approaching corners and speed-restricted zones.

ConnectedDrive: safety, comfort and infotainment

The new BMW 4 Series Convertible offers an unmatched combination of standard and optional driver assistance systems and mobility services. The intelligent link-up between passengers, their vehicle and the outside world ensures unbeatable levels of on-board comfort, infotainment and safety.

New features include the next generation of the Professional Media Package – featuring a significantly greater breadth of functionality and a high-resolution, contrast-rich colour display – operated in the familiar way using the perfectly positioned iDrive Touch Controller in the centre console, for even more convenient use. There’s also the Real Time Traffic Information (RTTI) service offering high quality, reliable traffic data; the latest-generation full-colour Head-up Display; Speed Limit Display; and LED headlights with glare-free High-beam Assistant.

The Active Protection safety package is now even more extensive thanks to the addition of the Attentiveness Assistant. The system’s electronics analyse driving behaviour on the basis of various on-board signals and if the system detects an increased frequency in the tell-tale signs of fatigue build-up, the Control Display prompts the driver to take a break by displaying a coffee cup symbol.

The latest-generation Professional Media Package also features a full speech recognition function and optimised voice control system to complete the portfolio of office functions offered by ConnectedDrive. Internet-based services, as well as calendar entries and text-based messages, can still be viewed in the Control Display of the iDrive operating system and read out via the Text to Speech function.

Finally, the BMW Connected app allows in-car use of innovative services like AUPEO!, web radio and social networks such as Facebook and Twitter, while the My BMW Remote app can be used to lock and unlock the vehicle, for example, or to remotely operate an auxiliary heating system.