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BMW Z4 Roadster gets its 343 hp M version
with major updates to the whole Z4 family 

BMW Z4 M Roadster

The M version crowns the Z4 roadster with 343 hp. It is differentiated from the ‘standard’ Z4 by its lower valance, large air intakes and dual styling lines on the bonnet.

APN,
27th October 2005.

Just a month after BMW unveiled its new Z4 Coupe concept at the 61st IAA Frankfurt motor show last September, here comes the turn of the Z4 Roadster to get, not only its facelift, but especially its top performance version: the M Roadster.

However, unlike the Z4 Coupe which will not be reach showrooms before next summer at the earliest, the enhanced Z4 roadster and the M Roadster will be launched at the 2006 North American International Auto Show (NAIAS) in Detroit next January.

Three-years after the Z4’s launch, BMW's M performance experts turned their attentions to the Z4, creating BMW’s fastest accelerating open-top, with 343 hp (106 hp per 1000 cc), 0-100 km/h acceleration of 5.0 seconds and an electronically limited top speed of 250 km/h (155 mph).

With the new "M" entry, the entire BMW Z4 Roadster range will get significant updates, featuring a new engine line-up, new gearbox options, styling enhancements and still the fastest opening fully automatic convertible roof in the world, in just under 10 seconds.

First, the Z4 M Roadster, then the Z4 facelift and technical enhancements.

BMW Z4 M Roadster

Like the current BMW M3 Coupé and Convertible, the new BMW Z4 M Roadster features the five-time International Engine of the Year Award winner for the three to four-litre category. The straight-six cylinder, 3,246 cc Motorsport engine delivers 343 hp at 7,900 rpm and 365 Nm of torque at 4,900rpm, with a six-speed manual gearbox and BMW M’s variable M differential.

Z4 M Roadster: diffuser between the 4 chrome-plated exhaust tailpipes.

Unlike the ‘standard’ Z4 that uses an electromechanical steering system, the new Z4 M Roadster uses a hydraulic power assistance system. The ‘standard’ car also uses Run-flat tyres as opposed to the M Roadster’s non-Run-Flat items – both features that M, as a separate division, believes give the car its own ‘M’ character.

These features are reinforced by BMW M’s floating compound high-performance braking system, originally conceived for the BMW M3 CSL, resulting in a 100 km/m to zero stopping distance of just 34 metres.

Visually, the new Z4 M Roadster is differentiated from the ‘standard’ Z4 by numerous details inside and out. From the front, the lower valance, large air intakes and dual styling lines on the bonnet clearly identify the M car while, at the rear, BMW M’s trademark quad-tailpipes and aerodynamic diffuser highlight the car’s potential.

The M-styling is finished off with exclusive M double-spoke 18-inch alloy wheels with 225/45ZR18 tyres on the front and 255/40ZR18s on the rear.

The Z4 M interior is complemented by new leather finishes in black.

The Z4 M Roadster is available in eight exterior colours, with three exclusive M colours – Sepang Bronze, Interlagos Blue and Imola Red, while the interior is complemented by new leather finishes in black, Imola red, Light Sepang bronze or Sepang brown and trim strips in Hexagon aluminium, black carbon leather or Madeira walnut wood.

In front of the driver a bespoke BMW M instrument binnacle featuring a black background with white numerals and red needles helps keep the driver in touch with vital driving information.

The BMW Z4 Roadster update

Coinciding with the launch of the Z4 M Roadster, the entire model range receives visual and mechanical enhancements. Engines first.

Z4 3.0si - Topping the new range is the Z4 3.0si, featuring BMW’s magnesium alloy in-line six-cylinder engine. With Valvetronic valve lift and VANOS valve timing, this version develops 265 hp at 6,600rpm and 315 Nm of torque at 2,750 rpm, to achieve zero to 100 km/h in 5.7 seconds (two tenths of a second faster than on the former model) and, if left unchecked, continues to a maximum electronically limited top speed of 250 km/h.

Three-dimensional design, like a sculpted body.

With this performance, the 3.0si consumes 8.61 litres/100 km over the combined cycle (manual transmission - see specs table).

The new engine outperforms its predecessor by 25 kW/34 hp or 13 per cent. Maximum torque is better by 5 per cent and is maintained consistently from 2,500-4,000 rpm.

Weighing just 161 kg or 355 lb, the six-cylinder is the lightest engine in its performance class, with a power-to-weight ratio of 1.18 kW per kilogram. To save weight in every respect, the crankcase is made of composite aluminium/magnesium. The bedplate and cylinder head cover, in turn, are made almost completely of magnesium no less than 30 per cent lighter than aluminium.

Operating with precision and as a function of the throttle pedal, Valvetronic controls the opening period and timing of the intake valves, minimising the energy required for the engine's charge cycle and thus using the fuel injected even more efficiently. A further advantage is that engine response is even better than before.

BMW Valvetronic is combined with BMW's infinitely adjustable dual-VANOS variable camshaft adjustment on the intake and outlet valves. The VANOS adjusters as well as the sprocket on the adjustment unit are made entirely of aluminium.

Exclusive M double-spoke 18-inch alloy wheels with 225/45ZR18 tyres.

Each of the two lightweight camshafts saves 600 grams, and the use of one single drive belt for all ancillary units again means less weight and a smaller risk of failure, with the second belt drive level no longer being required.

Further innovations include the electrical water pump which operates independently from engine speed and is controlled entirely according to the engine's current need for cooling.

The resonance intake system now operating in three stages provides even more torque at lower speeds by reducing flow losses to a minimum and ensuring a maximum cylinder charge, enlarging the speed range with its self-charging effect.

Z4 2.5i and 2.5si - Two straight-six 2.5-litre variants will be offered, the Z4 2.5si (218 hp) and 2.5i (177 hp).

Based on the same 2,497 cc engine, but differentiated by output, the 2.5si offers 218 hp and 250 Nm of torque, with a 0 to 100 km/h sprint  in 6.5 seconds, to a top speed of 239 km/h, with a consumption of 8.41 litres/100 km (manual) on the combined cycle.

BMW's M Sports division signature.

By contrast, the 2.5i delivers 177 hp/5800 rpm and 230 Nm of torque/3500 rpm (full specs in the table). This engine version replaces the former Z4 Roadster 2.2i, the extra capacity of the 2.5-litre power unit offering better performance and torque, particularly when accelerating from low speeds. The 0-100 km/h takes 7.1 seconds, with top speed of 229 km/h.

A further advantage is that the driver is now able to check the oil level on all engines by simply pressing a button to see the amount of oil currently in the engine.

All of the straight-six power units within the range come with a crankcase made of composite aluminium/magnesium, a special bedplate structure and a cylinder head cover also made of magnesium, together with BMW's Valvetronic, double-VANOS, four valve technology, adaptive knock control, and the resonance intake system.

Z4 2.0i - The only engine carried over from the outgoing range is the four-cylinder Z4 2.0i that was just launched in April 2005. Produced at BMW’s UK plant at Hams Hall near Coventry, the 1,995cc engine features BMW’s Valvetronic and double-VANOS camshaft adjustment on both the intake and outlet side, to develop 150 hp at 6,200rpm and 200 Nm of torque at 3,600rpm.

The lighter weight of this engine helps deliver sharp performance, dispatching the zero to 100 km/h sprint in 8.2 seconds before hitting a top speed of  220 km/h.

Direction indicators under the headlight in white instead of yellow.

Another feature is the DISA intake system, a BMW technology able to adjust the length of the oscillating pipes as a function of engine load. In conjunction with engine management, this particular technology ensures a level of responsiveness to the gas pedal previously offered only by a sports engine with individual throttle butterflies. At the same time two balance shafts guarantee better running smoothness at all times.

Transmissions - Like the Z4 M Roadster, all new Z4 models come as standard with a six-speed gearbox. Alternatively, customers purchasing 2.5si and 3.0si models can specify a six-speed automatic gearbox which, for the first time, features paddles on the rear of the steering wheel to select the appropriate gear manually.

The Sport Automatic allows the driver to take over transmission control whenever he wishes, shift paddles on the steering wheel ensuring fast gearshift with direct transition to the manual mode. When shifting down, in turn, Sport Automatic changes gears with interim gas much faster than a conventional automatic transmission.

All-new tail lamps and BMW’s Brake Force Display braking.

The integrated Steptronic function enables the driver to initiate a manual gearshift just by briefly moving the selector lever. to the appropriate gearshift gate or press the shift paddles.

Z4 Sport models - Sport versions feature 18-inch M double spoke or optional composite alloy wheel, M Sports seats covered in Active Sports leather upholstery, three-spoke M leather steering wheel and M Sports suspension.

Available with no less than four new wheel rims, the Z4 Roadster now offers even more customisation options than before. Apart from classic star-spoke rims, the new range of wheels also includes turbine wheel rim design (both rims measuring 8 x 17 inches).

Two different-sized rim options also allow the use of mixed wheels front and rear: one wheel in star-spoke design (8 x 17 inches at the front, 8.5 x 17 inches at the rear), one in ellipsoid-spoke design measuring 8 x 18 inches at the front and 8.5 x 18 inches at the rear.

Design update - Design update are moderate. From the front, the shoulder line extends all the way to the front air dam rather than stopping at the bonnet edge, a wider air intake dominates the lower valance and the kidney grille receives minor changes.

BMW Z4 3.0si

The Z4 3.0si version: foglamps follow the headlight shape.

The headlights themselves have been moderately modified, the direction indicators at the bottom of the headlight units now coming in white instead of yellow. Additionally, the headlights now include corona light rings as standard on all cars specified with Xenon lamps (standard on M Roadster models).

A further modification is the inclusion of the foglamps in the air intake, the foglamps themselves no longer being round, but rather narrow and horizontal in design, taking up the shape and looks of the headlights.

From the side, US-style side reflectors are integrated into the front wheel arches that also house new alloy wheel designs.

From the rear, all-new tail lamps feature Z8-style horizontal light conductor rods and BMW’s Brake Force Display braking system while a second spoiler lip adorns the rear air dam. The horizontal light conductor rods on the lights, in turn, form an optical unit with the third brake light, accentuating the width of the rear end above all at night.

While the rear air dam so far featured one spoiler lip at the bottom, the updated model now boasts a second lip also acting as a light contour visualising the wide track of the Z4 Roadster. The exhaust tailpipes are now even larger in diameter and are chrome-plated on the Z4 Roadster 3.0si.

Z4 3.0si: 265 hp, 315 Nm of torque and zero to 100 kph in 5.7 seconds.

The interior of the BMW Z4 Roadster gets its controls harmonised even better to one another in their material and looks, with the roll bars being finished in a galvanised ruthenium cover.

Four upholstery options are available in leather, glossy leather, cloth, and cloth/leather combined, with ten exterior and 12 interior colours, as well as five trim variants. The choice of five trim strip options made of wood and aluminium includes two aluminium strips, one of which has been updated and comes now with a fine, light longitudinally ground surface, the other with a classic, rough diamond look.

The former wood trim in light gloss grained poplar is now joined by dark grained poplar trim creating an elegant ouch within the interior.

All Z4 Roadster models feature a new paintwork colour choice including Monaco Blue, Flamenco Red, Silver Grey and Deep Green.

Suspension and dynamics - Carried over in its basic principles from the BMW 3 Series, the suspension has been modified in its spring and damper setting, as well as its kinematics and elastokinematics. More sporting performance comes with the option of a special sports suspension lowering the entire car by 15 millimetres. The runflat tyres featured as standard, in turn, have been specially developed to reflect the sporting character of the BMW Z4 Roadster.

DDC Dynamic Drive Control - The six-cylinder engines are available with the optional DDC Dynamic Drive Control which enables the driver to call up the Sports program, with engine management following an even more sporting and dynamic control map. The steering also becomes more sporting. If the car is fitted with automatic transmission, DDC revs up the gears to an even higher speed and shifts gears even more quickly than before.

BMW Z4 3.0si

New practical and active safety additions for sporty and normal driving.

The BMW Z4 features the latest generation of DSC Dynamic Stability Control which offers a wide range of functions in terms of sporting performance, safety, and comfort, with an integrated ASC stability control (it monitors wheel spin by taking back engine power and torque when required, applying the brakes selectively on the drive wheels about to spin. Other functions of DSC are the CBC Cornering Brake Control with its asymmetric division of brake pressure helping to prevent the car from swerving when applying the brakes slightly in a bend, and the DTC Dynamic Traction Control function which enables the driver to improve traction on surfaces with a low frictional coefficient by pressing a button, or to allow greater slip on the rear wheels adapted to current driving conditions.

DTC Dynamic Traction Control focuses on the enhancement of traction above all at low and medium road speeds, then gradually cutting back this function until the car has reached a medium level of lateral dynamics at speeds of about 70 km/h and/or lateral acceleration of approximately 0.4 g.

New DSC Functions - The latest generation of DSC Dynamic Stability Control offers the following additional safety and practical functions:

- Brake Pad Wear Control calculating the remaining distance the brake pads are still able to cover,
- DBC Dynamic Brake Control maximising brake pressure when applying the brakes in an emergency,
- Hill Set-Off Assist applies the brakes automatically for a few moments to prevent the car from rolling back when starting on an uphill gradient,
- Automatic Fading Compensation and Brake Standby (automatic pre-load of the brake pads).
- Automatic Dry Braking of the brake discs on wet surfaces.

Brakes - The 17-inch brake system on the Z4 Roadster 3.0si is brand-new, featuring inner-vented brake discs front and rear. On all other Z4 Roadsters (with the exception of the Z4 M Roadster), in turn, the brake discs are inner-vented only at the front.

Electromechanical power steering with BMW's rear-wheel drive.

Electric Power Steering - The BMW Z4 Roadster benefits in particular from rear-wheel drive characteristic, keeping the steering completely free of drive forces at all times, especially with the electromechanical power steering. EPS (Electric Power Steering) features an electric motor on the steering column and a worm gear supporting steering forces. Steering forces are passed on to a mechanical steering transmission via an intermediate steering shaft, the transmission helping to provide the right steering lock by means of tie-bars.

Thanks to the software control, EPS allows a high level of flexibility in the car's steering characteristics, an optimum compromise between the steering damping effect and feedback from the road, as well as low steering forces at low speeds and when manoeuvring. A further important function is the centering effect of the steering, with the steering wheel returning perfectly to its straight-ahead position after a bend. Whenever the driver activates the sports mode on a car fitted with the optional DDC Dynamic Drive Control, steering assistance is reduced to provide an even more sporting feeling on the road.

A further advantage of Electric Power Steering is the reduction of fuel consumption, since the system does not require any energy when driving straight ahead without any movement of the steering wheel. The reduction in fuel consumption can be up to 1 litre every 400 kilometres or 250 miles compared with conventional hydraulic steering.

Unlike the ‘standard’ Z4 that uses an electromechanical steering system, the new Z4 M Roadster uses a hydraulic power assistance system. The ‘standard’ car also uses run-flat tyres as opposed to the M Roadster’s non-run-flat tyres.

Tyres - The Z4 Roadster 2.5i and 2.0i come as standard on 225/55 R16 runflat tyres, while the Z4 Roadster 3.0si features 225/45 R17 runflat tyres. Reinforced side flanks with additional inserts and temperature-proof rubber compounds, interacting with EH2 (extended hump) rims, prevent the tyres from being compressed under lack of pressure or jumping off the rims. As a result, the driver is able to continue for up to 250 kilometres or 155 miles on one or even several empty tyres, at a speed of up to 80 km/h or 50 mph and with an appropriate style of motoring. All control systems remain fully functional even in this case.

The runflat tyres are combined with an electronic Tyre Pressure Control System likewise featured as standard and warning the driver in good time of a possible loss of pressure by means of an optical signal in the dashboard. This system responds after just a few minutes on the road or, alternatively, at a speed of 15 km/h.

The rims on the BMW Z4 Roadster are fully compatible with conventional tyres and wheels. The driver can fit a "normal" tyre whenever necessary. Runflat tyre technology comes on both summer and winter tyres.

Z4 Roadster dimensions

Advanced Safety Electronics - The Z4 Roadster is the first car to feature BMW's Advanced Safety Electronics (ASE) masterminding four (front and side) airbags. The ASE satellites, in turn, control the activation of the airbags and belt latch tensioners individually according to the specific requirements in each case. Where necessary, ASE also monitors the Safety Battery Terminal to ensure it is properly disconnected in a collision, switching off the alternator and fuel pump, opening the central locking, and switching on both the interior lights and the hazard warning flashers.

In conjunction with a car telephone and the Professional or Business navigation systems, the BMW Assist telematics service sends out an emergency signal in the event of an accident, transmitting the current location of the car and establishing a voice link with the Emergency Headquarters.

Two-stage brake lights - The new Z4 Roadster benefits too from BMW's two-stage brake lights. Under normal application of the brakes, the brake lights come on in their standard configuration at the rear and in the third brake light positioned higher up. Whenever the driver brakes hard or when ABS intervenes, the illuminated areas in the rear lights are enlarged accordingly, generating an even clearer signal which a motorist following from behind will intuitively perceive as an emergency braking manoeuvre.

Variable Roof Box - To provide more space when the roof is closed, the variable roof compartment (made of a special synthetic material) can be unlocked and folded up like a collapsible box, increasing luggage capacity from 240 to 260 litres. To avoid damage to the roof or luggage within the boot, a safety circuit prevents the electrohydraulic roof from opening as long as the roof compartment is closed. An aluminium railing for the rear lid is available as special equipment.

The Z4 Roadster requires neither a tonneau cover nor a roof flap. The noise level inside the car as well as climate comfort, finally, are optimised by an additional roofliner both on the fully automatic and the manually operating roof.

Z4 M Roadster dimensions

The manually opening roof is held in position by a central lock on the windscreen frame, opening and closing with one hand. As an option the Z4 Roadster is also available with a fully automatic power roof. At the press of a button, the complete process of opening - or closing - the roof takes place with electromechanical control in just under 10 seconds. Electrohydraulic control serves to fold up the roof and hold it in position, the system then operating in exactly the opposite direction when closing the roof.

An optional wind deflector system is available to reduce draughts. Two deflectors are fitted in the opening in the two rollbars and remain in position, with a net being tightened between the rollbars within an additional frame. The net comes out easily and can be kept in a special holder within the luggage compartment. A hardtop is also available as special equipment.

Headlights - The BMW Z4 Roadster is fitted as standard with dual halogen headlights, high-power H7 bulbs for the low and high beam homogeneously illuminating the road ahead and making a significant contribution to active driving safety.

Static bi-xenon headlights are available as an option. Distribution of the high and low beam is achieved with the electromagnetical movement of a shutter over the xenon bulb, to alter the size and direction of the beam.

Two Navigation Systems are available, with DVD Memory as an Option. The Business navigation system integrated in the dashboard uses data provided by a DVD with a high-density memory - the whole of Europe fits on one DVD.

Combined with a fast processor, the navigation system is able to immediately calculate a new routing whenever. And since this radio navigation unit is a fully integrated system, it also enables the driver to control the on-board computer, radio and telephone all from one position. The small monochromatic monitor for the navigation system is able to present short messages, and both the CD player as well as the CD changer are fully compatible with MP3 requirements.

The Professional navigation system comes with a retractable 16:9 colour monitor of the latest generation positioned right in the middle of the instrument panel. Swivelling round its own axis, the colour monitor opens up automatically as soon as the driver or passenger press a button or switch on the radio, then closing again once the driver takes the key out of the ignition. The monitor adjusts electrically or manually at the touch of a button and may also be folded in completely when not required. Using a new screen technology, the display is easy to read under all light conditions and prevents reflections on the windscreen thanks to the special anti-reflection film beneath the surface.

Both navigation systems may be combined with a telephone fitted in the car also as special equipment.

Current prices of the Z4 roadster start in Germany from 28,900 Euros for the Z4 2.0i version, up to 40,400 euros for the Z4 3.0si. The Z4 M Roadster version is expected to be priced above 50,000 euros. You can get all market-specific information (versions, prices and options) from www.bmw.com.

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