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.
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
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
First, the Z4 M Roadster, then the Z4
facelift and technical enhancements.
BMW Z4 M
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
M Roadster: diffuser
between the 4 chrome-plated exhaust
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.
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.
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
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
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.
M double-spoke 18-inch alloy wheels with
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.
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
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
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.
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
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
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
tail lamps and BMW’s Brake Force Display
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
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
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
Z4 3.0si version: foglamps follow the
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.
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
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.
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
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.
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
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.
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
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
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.
systems may be combined
with a telephone fitted in the car also as special
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.