BMW's 1-Series opens up with the local arrival of the four-seater Convertible.

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Top of the range is the 135i Convertible powered by a 225kW, 3.0-litre straight six cylinder engine with Twin Turbo and petrol direct injection that can be recognised by its subtly modified, standard M Aerodynamics Package. The engine range is complemented by a further six cylinder in the 125i Convertible, which produces 160kW, and a four-cylinder engine with Vanos and Valvetronic producing 115kW in the 120i Convertible.

The entire series features an electrohydraulically driven fabric roof that opens and closes within 22 seconds — and if necessary can be operated while on the move at low speed.

Recognisably BMW

The characteristic features of the front skirt, door sills and rear skirt are identical in their detail to those on the BMW 1 Series Coupé. Distinctive though is the flared shoulder line which runs parallel to the road. The shoulder line follows through from the bonnet past the A-pillar right through to the boot lid, connecting the front and rear with each other and forming a surface which encompasses the whole interior.

The tail view is largely influenced by the visual effect of the soft top. If the roof is open, the horizontal body line unfolds its full effect. Because the canopy top is lowered completely into the boot, the Convertible appears flat and elegant at the rear. If the soft top is closed the widening contour below comes into its own.

The boot lid finishes in a discrete top edge with an integrated third brake light. This aerodynamic element emphasises the shortness of the tail and also provides additional downward pressure on the rear axle at high speeds.

When it comes to the canopy, a soft top option is available as an alternative to the classic black or beige. This "worldwide first", which is anthracite with silver effect, is exclusively developed for the Convertible, by combining a normal woven fabric which is then interwoven with fine shiny metallic fibres. This gives the material a high quality metallic shimmering surface impression, which produces charming reflections in sunlight.

Amongst the three derivatives, the most clearly sportily orientated BMW 135i Convertible differentiates itself by the standard modified M Aerodynamics Package taken from the M Sports Package. The extra large central air intake runs out upwards beside the number plate. The flanking, smaller air inlets are bordered by slightly contoured flaps. So the front looks wider than the other models. A further distinctive feature in the front aspect is the chrome plated bars in the kidney grilles.

The side sills of the 135i reduce the visual height of the side even further by incorporating an additional light flange. And, at the rear, the car's wide track is clearly underlined. The matt black diffuser is integrated into the rear air dam below the bumper, while a further visual accent is created by the dark chrome exhaust pipe end baffles.

Sit inside

Building on the 1 Series Coupé, the interior design was adapted to the requirements of an open vehicle. The transition from exterior to interior is formed by a chrome line running all round as standard on the 135i and 125i, and as an optional extra on the four-cylinder model.

The upper area of the instrument panel is in black, with a graining on the surface of the instrument area extending to the door covering and central console. The central area, where the operating controls are for the entertainment and air conditioning systems, melts into the instrument panel and runs down to the central console between the two front seats.

A galvanised pearlescent finish is used throughout on elements like the door openers, the adjustment units for the air vents, the operating buttons for audio and air conditioning as well as the decorative clasps on the leather steering wheel.

An insert is integrated into the door cladding between the top capping line and the armrest. The available leather option, which is specially extended for the Convertible in its scope, includes the arm rests on the central console and the doors in addition to the seat finishes.

The optional full leather interior features sun reflective technology to reduce the heating up of the surfaces in direct sunlight.

The optional automatic climate control (standard on some models) was designed to work even with the roof open. As soon as the convertible mode is selected, the ventilation control reacts less to the interior temperature and more to the outside temperature and sunlight factors.

The optimum wind deflector, which reduces the air turbulence in the interior at higher speeds, can be firmly fixed by hand adjustments via inlets in the side cladding at the rear of the car if required.

Load it up

Luggage space is 260 litres with the roof open, which grows to 305 litres as soon as the soft top is closed: the variable cover which separates the canopy from the luggage space can be swivelled upwards.

The rear seat backrest gives the Convertible a further increase with the optionally available load opening into the rear of the car's interior including a transit bag that's large enough to take, for example, a full size golf bag.

Even if the roof is open there's space for two full size golf bags to be stowed crosswise. If one is pushed lengthwise into the transit bag then there's additional room in the luggage space for additional bags for example. A zip gives access to the transit bag contents from the rear of the car.

Need to carry more golf bags? There's a luggage rack — except on the 135i Convertible — which is available as an original BMW accessory and is fastened to the rear of the car. It can accommodate two bicycles and can be folded out of the way easily whether it is loaded or unloaded.

The grunt

All petrol engines in the Convertible were designed within the BMW EfficientDynamics development strategy and so feature several innovations to optimise fuel consumption and emissions — like the electronic power steering included in all models other than the BMW 135i Convertible that only uses energy when steering assistance is really needed.

The sportiest variant is the 135i Convertible, powered by the most high performance straight six cylinder unit in BMW's engine programme. Combining Twin Turbo and High Precision Injection technology, the all-aluminium power unit eliminates the typical "lag" of traditional turbo engines. It outputs 225kW from 2979cc at 5800rpm, while maximum torque of 400Nm is maintained from 1300 to 5000rpm, accelerating the car from 0 to 100km/h in 5.6 seconds, while top speed is limited to 250km/h by the engine electronics.

Fuel consumption is a claimed 9.8 litres per 100km.

To complement the engine, the range topper comes with M Sports Suspension, an individual setting of DSC (Dynamic Stability Control), an electronically controlled locking function for the differential, a model specific direct control map for the Servotronic steering support and a spontaneous reaction accelerator control map.

The 125i also has a straight six cylinder under the engine hood. The normally aspirated power train mobilises 160kW at 6100rpm and a maximum torque of 270Nm at 2500rpm from a capacity of 2996cc. These figures are good for a top speed of 237km/h, while the 100 km/h mark from standstill is reached in 6.9 seconds. Fuel consumption is 9.1 litres per 100km.

And the four-cylinder unit in the 120i Convertible produces 115kW at 6400rpm and, at 3600rpm, it provides maximum torque of 200Nm. This gives acceleration from zero to 100km/h in 9.2 seconds and a top speed of 214km/h.

As an alternative to a manual gear box all new BMW 1 Series Convertible engine variants can be combined with a six-speed automatic transmission as an option. Thanks to the Steptronic function, the driver can also shift gears manually by using the selector lever on the central console or by shift paddles on the steering wheel of the six-cylinder models.

On the road

Electric power steering (EPS) comes with integrated Servotronic function for speed-related steering assistance. Result: more steering precision and enhanced comfort and reduced fuel consumption. The BMW 135i Convertible features conventional hydraulic power steering.

As an option the Convertible can be equipped with active steering: at lower speeds the same turn of the steering wheel as at higher speeds produces a larger angle of turn. This means that parking requires only a slight turn of the steering wheel and minimum effort is required. At higher speeds holding course is made easier.

Not optional but standard is Dynamic Stability Control (DSC). Besides incorporating typical ABS for braking, DSC also applies the brakes specifically on individual wheels in demanding situations and reduces engine power in order to prevent oversteer and understeer. Components of the DSC include the Acceleration Skid Control (ASC) which prevents the drive wheels from spinning when driving away, the Cornering Brake Control (CBC), to stabilise the car when applying the brakes while cornering and Dynamic Traction Control (DTC) which allows more slip on the drive wheels for better pulling away on loose surfaces.

Safety specs

Safety is based firstly on the solid body of the whole model series: high strength steel, additional reinforcement and special deformation elements keeping forces away from the passenger cell.

Torsional rigidity values are orientated to the safety designed into the 3 Series Convertible.

Inside, four air bags (front and side) come standard — as do the crash optimised seats: upholstered head restraints and backrests reduce injury risk considerably in a rear impact on the vehicle. All seats are equipped with three-point automatic belts and head restraints and the rear seats are fitted as standard with Isofix anchors.

In the case of a frontal collision the foot pedals swing away and the foot supports collapse under load which further reduces the risk of the driver suffering foot injuries.

The Convertible is also equipped with a rollover sensor, which continuously captures the vertical and horizontal movements of the vehicle. As soon as the safety electronics registers the danger of the vehicle turning over, two rollover bars are extended in fractions of a second; they are normally stored sunk behind the rear seat head restraints. At the same time the front seat belt tensioners and the head thorax air bags are activated.

Pricing
BMW 120i Convertible (Manual): R308 500
BMW 125i Convertible (Manual): R354 500
BMW 135i Convertible (Manual): R432 500
BMW 120i Convertible (Automatic): R323 000
BMW 125i Convertible (Automatic): R371 100
BMW 135i Convertible (Automatic): R450 200