Specials & Features

With the 2008 Z4 M Roadster and Z4 M Coupe, BMW brings the Z4’s advanced sports car technology and BMW M’s incredible 330-horsepower 6-cylinder engine together for the ultimate two-place performance vehicle.

A wide range of new BMW and BMW M developments in suspension, steering, brakes, stability systems, safety features and luxury and convenience feaures are also a part of the Z4 M Roadster and Coupe’s genetic makeup.

The BMW M 6-cylinder engine: thoroughbred performance
At the heart of the Z4 M Roadster and Coupe is BMW M's 3.2 liter 6-cylinder inline engine made famous in the M3 Sedan And Convertible. This award-winning engine has been characterized as “ferociously powerful“ by Car and Driver (May ‘03) and “an engine that likes to rev“ (Road & Track, December ‘03). The British magazine Engine Technology International has named it Best Engine of the Year for 3.0 to 4.0 liters for five years in a row. Now this remarkable unit gets to power lighter, even more agile BMWs than the M3s.

Statistically speaking, the results are dramatic: delivering 330 horsepower at a high-revving 7900 rpm, the internally-designated S54 engine propels the 3200-pound Z4 M Roadster to 60 mph in just 4.9 sec. Maximum speed is electronically limited to 155 mph; speculation about what the top speed might be without the limiter will intrigue enthusiasts, but BMW makes no claim in this regard.

In its broad concept, this engine shares its inline format with other BMW 6-cylinder engines. Virtually all its engineering details, however, are unique and targeted to the very highest level of performance. Unlike other Z4 engines, which employ lighter materials for their block and cylinder head, the S54 combines a cast-iron block with its aluminum head to achieve the engine’s 3.2-liter displacement without lengthening the block.

The block accommodates this engine’s bore and stroke of 87.0 x 91.0 mm, both larger than the dimensions of other BMW 3-liter engines. However, playing larger roles than increased displacement in the 75-hp increase over the most powerful regular-production 6-cylinder engine is the special induction, combustion and exhaust engineering, together
with its execution as a high-rpm engine. The starring role here is played by a cylinder head that could be termed “exotic.” Its key features include:

Double VANOS steplessly variable valve timing on the intake and exhaust camshafts. Though this system appears in all other current BMW engines, in the M unit it varies timing over a wider range and contributes in a major way to the engine’s ultra-high power output.

VANOS pressure pump. In regular-production BMW engines the main oil pump supplies the pressure to operate VANOS; here the VANOS system has its own radial-piston hydraulic pump. Integral to the exhaust camshaft’s VANOS mechanism, the pump produces up to 120 bar (1740 lb./sq in.) of pressure to vary valve timing more quickly at the very high rpm this engine reaches. BMW M refers to its VANOS system as High-Pressure Double VANOS; it is also used in the M5 and M6’s 500-hp S85 V10 engine.

Unique valve mechanism. All BMW engines have an efficient valvetrain. Yet for an engine with the S54’s rpm potential, BMW M engineers needed less reciprocating mass than in the regular-production engines.

To achieve this, they created a unique actuating mechanism, using extra-light finger-type rocker arms. Pivoting on their own shafts (one on the intake side, one on the exhaust), these small arms provide the actuating surface between camshaft and valve. As the entire arm does not move the distance of valve lift, its effective reciprocating mass is less than its actual mass. All told, the valvetrain’s effective mass is 30% less than in the BMW 6-cylinder engines that have bucket-type hydraulic lifters; in turn, this allows lighter valve springs, which further reduce inertia. The system also has less friction.

As there is no hydraulic maintenance of valve clearance and it does have to be inspected periodically. It is unlikely that clearance will ever require adjustment, but if so it is done with shims (tiny metal discs of various thickness) without removing the camshafts.

Whereas the “regular” 6-cylinder engines have a simplex (single) camshaft drive chain or chains, the S54 has a full duplex (double) chain driving its camshafts. As usual with BMW engines, the chain is hydraulically tensioned and needs no periodic adjustment or replacement.

Extra-high compression ratio. At 11.5:1, the M engine has the next-highest ratio in current BMW production, topped only by the M5‘s and M6's 12.0:1.

Machined surfaces. More “engineering finery” again: combustion chambers and intake ports are completely machined, for smoothness that facilitates airflow. The exhaust ports are partially machined. For durability, the valve seats are of especially hard steel. A 3-layer stainless-steel head gasket ensures effective sealing of the head to the block.

Head casting and sealing. Extreme strength in the cylinder head is achieved by making it a single aluminum casting. Though elaborate, this construction also saves a significant 29 lb. As this weight reduction is at the top of the engine, it helps lower the car’s center of gravity.

Induction system:
BMW M tradition, state-of-the-art technology
The S54 engine manifests an important BMW M tradition: an individual throttle for each cylinder. Positioned much nearer to the cylinders than a single throttle can be, these bring atmospheric pressure practically right to the cylinder. The “lag time” inherent in airflow into the cylinders is thus greatly reduced and the engine can react more quickly to throttle movements.

Via the accelerator pedal and its two potentiometers, the driver gives the commands, in turn processed by the engine control module and received by a DC servo motor. The motor drives the throttle shaft through a tiny gearbox.

Upstream of the throttle bodies are the six intake trumpets, made of weight-efficient fiberglass-reinforced PA6 thermoplastic; these are laser-welded into the induction plenum of the same material to form a single assembly.

M Dynamic Driving Control provides Normal and Sport settings for throttle response. In Sport, selected via a console switch, the ratio of throttle opening to pedal movement is increased so that apparent engine response is even quicker. Even the transitional response of the electronic engine controls is altered to suit. Drivers tend to find one or the other setting more to their liking, or choose them according to driving conditions or mood. The system always defaults to Normal when the engine is started.

Together with VANOS, this elaborate induction system adds to the engine’s immense breathing and fuel/air processing capabilities.

Exhaust system: engineered for free flow
For the Z4 M Roadster and Coupe, it was necessary to develop a newly routed exhaust system because their underbodies are quite different from that of the Z4 3.0i and Z4 3.0si Roadsters and Coupes.

After the partially-machined exhaust ports, the system begins with two snaking stainless-steel headers serving three cylinders each. These elaborate headers are “hydroformed“ under high pressure with liquid inside them, which ensures even distribution of the forming pressure and thus consistent wall thickness. In turn, this process allows stainless-steel walls only 1mm thick (about 1/25th of an inch), not only helping save weight but also hastening engine warmup as there is less metal to heat up after a cold start. Each header is a single piece, thus not welded-up as are most headers.

For effective emission control during engine warmup, the forward catalytic converters are right at the headers. From these catalytic converters rearward, the dual exhaust system continues through mufflers, resonators, two additional catalysts and finally four chrome outlets that speak the authoritative tones of M Power. In its sound quality, the exhaust syste found in the Z4 M Roadster and Coupe are tuned for a somewhat milder tone than that of 6-cylinder M vehicles in the past.

High-performance lubrication and cooling
To help ensure adequate lubrication under the high cornering, acceleration and braking loads the Z4 M Roadster and Coupe attain, the S54 engine employs a “semi-dry-sump” oiling system. Particularly in hard cornering to the left, it is critical to ensure return of oil to the pan; therefore, integrated into the gear-type pressure pump is a scavenging pump that collects oil from the right side of the small forward oil sump and pumps it back into the main, larger rear sump. This rear sump is almost completely closed off from the rest of the system, and thus able to hold the oil necessary for lubrication throughout the engine. Specific return passages are also incorporated into the intake (left) side of the engine to help ensure ideal oil flow under all operating conditions.

The graphite-coated aluminum pistons are cooled by oil spray; each valve’s rocker arm is sprayed with oil just before it is loaded by its camshaft lobe.

A thermal sender monitors oil level and temperature. If the level drops low, a warning appears in the instrument cluster; the tachometer face includes the oil-temperature gauge.

The cylinder head incorporates crossflow cooling; this promotes consistent temperatures from the front to the rear of the head, helping minimize distortion and wear under the extreme heat such a high-performance engine develops when its full power is being exploited.

The high-rpm concept
High engine speeds are essential to achieving high power from moderate displacement, but they pose challenges; engineers must ensure that durability standards are met at these levels. The S54 engine’s maximum power occurs just below its 8000-rpm limit at 7900 rpm.

To achieve this revving capability, the engineers applied a number of detail measures. A forged, nitro-carbonized steel crankshaft provides great strength in this critical component. Forged-steel “cracked” connecting rods eliminate the need for bolt sleeves and thus reduce reciprocating weight.

A unique water pump plays a role too. The crossflow cooling requires high coolant flow. To achieve this, the engineers developed a pump with 3-dimensionally contoured vanes. Such contours would have been inordinately costly to produce in metal, so BMW M developed a novel pump design. Each vane is a small plastic casting, pressed into an also-plastic rotor and then welded into place. Also adding cooling efficiency is a ring thermostat, which imposes less resistance to coolant flow than a conventional plate thermostat.

Electronics play their role too. The engine’s control module – specifically developed for the Z4 M application – calculates and adjusts the ignition and fuel injection at each cylinder individually every 6 degrees of crankshaft rotation. Ignition occurs through a very small-diameter “pencil” coil at each cylinder.

Great looks too: the view under the hood
Following a long BMW M tradition of visually attractive machinery, the S54 engine’s appearance is as beautiful as its engineering. Tubing – for the idle air supply, fuel to the injectors, fuel from the fuel pump – is stainless steel. Housed in cast aluminum, the VANOS mechanism projects prominently forward of the cylinder head. Stainless-steel screws secure the camshaft cover; chrome rings hold the induction trumpets to the ports. The “M” logo and a special M oil filler cap adorn the front of the camshaft cover.

Z4 M Roadster and Coupe drivetrain: getting S54 power to the road
Like every M Car to date, the Z4 M Roadster and Coupe transmit power to the road via classic rear-wheel drive and include some premium and fascinating engineering into its drivetrain.
A transmission for sporting enthusiasts. The Z4 M Roadster and Coupe come with a 6-speed manual transmission. There is no automatic transmission offered. It is a ZF Type H gearbox, which features evolutionary improvements:
• Even more effective synchronization of shifts
• Lighter and more pleasing feel as shift lever is moved from gear to gear
• Firmer engagement of gear once selected
• Shorter “throws“ from neutral to each gear
• Use of lifetime transmission oil, which never needs to be changed
• “Clean bearings“ design for main transmission bearings; protects bearings from contamination, ensures adequate lubrication at all times and therefore enhances durability.
As in other M models, the shift pattern on the gearshift knob is illuminated attractively at night.

Super-sized differential unit. A specific subframe allows equipping the Z4 M Roadster and Coupe with a heavy-duty differential with gears made of a special high-strength steel alloy to achieve quietness and durability. As at the front spoiler, rear diffusor and elsewhere along the underbody, airflow under the vehicle is carefully managed and targeted; here, a ribbed differential case and NACA air intakes for the differential unit help keep the oil cool.

M Variable Differential Lock. Together with the German division of GKN Viscodrive, BMW M engineers developed a special mechanical limited-slip that also appears in the M5 and M6. This M Variable Differential Lock specifically addresses low- and split-traction situations in a way that reinforces sporty handling while contributing to remarkable slippery-road abilities.

Any time a speed difference develops between the two rear (driven) wheels, a shear pump, driven solely by this difference, develops pressure in the silicon viscous fluid in which the lock operates. In turn, this pressure is directed to a multi-disc clutch that transfers driving torque to the wheel with the better road grip (“select high”). The greater the speed difference between the two wheels, the more aggressively the clutch engages. As soon as the difference between the two wheels’ speeds begins to diminish, the clutch starts to ease off.

This mechanism achieves its sophisticated action by entirely natural means. There is no external pump, no external source of lubrication or operating fluid. The very motion to be controlled – differences in speed between left and right wheels – generates its locking action. Viscous fluid is so-called because it develops internal force (via an increase in viscosity) whenever it is sheared; this is why the relatively small difference between one wheel speed and the other can generate the necessary action.
Dynamic Stability Control. This electronic traction and stability system, standard on all current BMWs, complements the M Variable Differential Lock.

DSC optimizes traction by electronic means, sensing wheel-speed differences and reducing engine torque and/or applying individual rear-wheel brakes. The crucial difference to the Z4 M Roadster driver between the M Variable Differential Lock and the DSC traction function is that the former in no way impedes power delivery, and is hence suitable for performance driving.

Yet in fact, even DSC’s traction function is calibrated to M-specific parameters. In combination with the fast-reacting engine, performance-oriented gearing and M Variable Differential Lock, its logic achieves the desired traction optimization in an M-compatible way…in other words, without undue interference with the differential lock’s ability to get power to the road.

The DSC stability-enhancing function is essentially unrelated to traction. Sensing differences in wheel speed in a critical cornering or avoidance maneuver, DSC detects any deviation from the normal cornering path (abnormal understeer or oversteer) and gently applies individual wheel brakes to help the driver keep the vehicle on the intended path.

As in other recently introduced BMW models, the Z4 M Roadster’s and Coupe's DSC system incorprates:
• Brake Drying. Acting on input from the windshield wipers’ rain sensor, the brake pads are periodically brought up to the rotors – just enough to eliminate any film of water between the pads and rotors, but not enough to cause any brake applications. This improves brake readiness in wet driving conditions.
• Start-off Assistant. Keeps the vehicle from rolling backward when stopped facing uphill. For 2 seconds after the brake pedal is released, the driver can then move off from rest without the car rolling back.
• Modulated ABS function. Thanks to new “analogized” control of the DSC brake valves, the anti-lockup function (ABS) is smoother than before. Instead of simply being fully applied and released, the application and release of these valves is now modulated.

Some DSC braking functions found in regular-production BMW models, such as Comfort Stop, are not included in the Z4 M Roadster because of its ultra-sporty driving character.

The Z4 M Roadster and Coupe chassis: extensive new engineering by BMW M
Starting with the Z4’s already excellent chassis engineering – Motor Trend commented in its May ‘05 issue that the Z4‘s “sport suspension and solid chassis make this car a thrill to drive on canyon roads“ – BMW M has endowed the Z4 M Roadster and Coupe with typical M modifications that further enhance handling and tailor the cars' road capabilities to M’s higher performance level.

Front suspension. While retaining the Z4’s basic concept – strut-type with forged-aluminum lower arms – the M engineers created an essentially new version with:
• A wider front track (by 0.5 in.)
• Newly configured lower arms, still of forged aluminum; more complex shape with open sections for lightness, similar to those of M3s
• New steering knuckles, bolted to the struts (saves weight, sharpens steering response)

Such changes, subtle yet deep-reaching, are – as good as the basic BMW model is – key to achieving the “beyond exceptional” reflexes of an M model.
Rear suspension. Though modifications to the Z4’s Central Link (multi-link) rear suspension are less extensive than at the front, they are significant. Among others, the following major M elements are shared with M3s:
• Rear subframe – larger and stronger; accommodates differential with M Variable Differential Lock
• Wheel bearings
• Central (longitudinal) Links
• Arrangement of anti-roll bar.

As at the front, these modifications sharpen handling capabilities.
Ride height and suspension calibration. Like the Z4’s sport suspension, that of the Z4 M Roadster and Coupe are set lower compared to the standard Z4’s setup. Unlike the Z4, however, the M versions get an all-around new calibration of springs, shock absorbers, anti-roll bars and bushings to BMW M parameters; this includes specific auxiliary springs at the front and rear.

A new steering system. Alone among BMWs, Z4s have electrically assisted power steering. With this system’s vehicle-speed-sensitive power assist, it is notable for its combination of reduced driver effort in parking and at low vehicle speeds, and good road feel at higher driving speeds.

BMW M has somewhat different priorities: a greater emphasis on absolutely accurate road feedback and ultra-spontaneous response to the driver’s commands at the steering wheel. In this context, higher parking and low-speed efforts are acceptable. Thus M gave the Roadster and Coupe a hydraulically-assisted rack and pinion with a power-steering pump calibrated with assist characteristics optimized for the Z4 M Roadster and Coupe. This system reduces parking efforts somewhat, but not to the degree that vehicle-speed-sensitive assist does.

BMW M’s most advanced brake system. The Z4 M Roadster and Coupe come standard with BMW M’s most elaborate brake concept: compound, cross-drilled 4-wheel ventilated discs.

The brake rotors are 2-piece, with an aluminum “hat” and a cast-iron outer portion that is the actual friction surface. The hat and outer portion are connected by steel pins on which the aluminum and cast-iron portions, because of their differing expansion rates, can move relative to each other. This is an elaborate, costly construction that cuts unsprung weight and eliminates rotor deformation under hard-braking, high-heat conditions. In practical terms, this means virtually no tendency of the brakes to vibrate when hot, and also virtually no likelihood of the rotors cracking under the extreme heat conditions that might be encountered in driving on a race track.

At the front, the discs are of 345-mm diameter x 28-mm thickness (13.7 x 1.10 in.); at the rear, the discs measure 328 x 20 mm (12.9 x 0.79 in.). Cross-drilling, visible through the wheels, enhances heat dissipation beyond that provided by the rotors’ internal ventilation, further increasing the brakes’ resistance to fade, improving braking effectiveness in wet weather and reducing unsprung weight. Given the Roadster’s and Coupe's light weight, this system achieves phenomenal braking.
Wheels and tires: ultimate style and grip. M Double Spoke wheels, with a very open configuration to help get plenty of cooling air to the brakes, complement the Z4 M’s body design with a boldly sporty, yet elegant look. Sized 18 x 8.0 front and 18 x 9.0 rear, they are connected to the road by suitably wide, low-profile, high-speed-rated tires sized 225/45ZR-18 front and 255/40ZR-18 rear .

As with other BMW M models, the Roadster's and Coupe’s tires are not run-flats; run-flat tires meeting M requirements are not yet available. Also, the M exhaust system’s bulk precludes a spare tire. Thus like other BMW M models, the Coupe comes standard with the M Mobility System for use in case of a flat tire. A Tire Pressure Monitor alerts the driver to a significant loss of tire pressure.

M Mobility consists of a container of rapid sealant, a small compressor, and a hose to connect the compressor to the damaged tire. All this is carried in a container in the trunk; the system can seal punctures up to approximately 1/4 inch across. Omitting the spare tire saves about 45 lb. of weight.

The Roadster’s and Coupe's wheels incorporate the so-called Extended Hump rim shape, which helps keep the tire on the rim in case of deflation.

Z4 M Coupe design
The Coupe encloses its two seats and a larger cargo area in a graceful fastback body that retains the unique Z4 aesthetic character and the special BMW M details that distinguish the Z4 M Roadster from its Z4 Series counterparts.

And as the Coupe shares all the BMW M engineering distinctions with the Roadster, it brings the same level of thoroughbred performance to this handsome new shape. Now, enthusiasts of BMW M‘s brand of ultimate road capabilities have a doubly tempting choice of 2-seaters: the open-bodied Roadster with its fast-action power softtop or this closed-body Coupe.

In its lower-body contours, the Z4 M Coupe corresponds mostly to the Z4 M Roadster‘s newly refined front end and hood lines; long-hood, cabin-back proportions; and double beltline along the sides. In particular, the lower, stylistically primary beltline begins above the outer headlight, curves upward and then downward into the door hiking sharply upward again and finally heading downward to conclude at the rear edge.

Because the Coupe’s upper beltline has a visually longer continuity as it extends on past the new rear-quarter window with its traditional BMW “Hofmeister kink,“ the lower one even more boldly evokes the fender line of classic Grand Touring coupes. Even stronger in its esthetic impact is the new fastback roofline. For one thing, in cross-section its center depression or “channel“ is reminiscent of certain GT coupes of the Italian coachbuilder Zagato in the Fifties and later. In profile view, the roof parallels the side windows’ top edge, then continues on down to meet a crisp, stand-out cutoff point that forms a rear spoiler. Then it concludes at the bumper as the bottom edge of a rear hatch. Everywhere you look, the contours are masterfully drawn.

This hatch, encompassing the entire roof portion from the rear window’s top edge to the bumper, opens wide and high to provide excellent access to a relatively roomy, velour- lined cargo area that can accommodate two golf bags.

The M look: subtle and purposeful
The transformation from a regular-production BMW model to a BMW M creation is always subtle, always purposeful. The Z4 M Roadster and Coupe are clearly in this tradition.

At the front, the fascia – bumper, spoiler, grille framing – makes a statement both esthetic and functional. The traditional BMW “kidney” grilles are deep in their openings. Their vertical slats are black, harmonizing with the three black-trimmed air-intake openings underneath. To satisfy the engine’s and brakes’ cooling requirements, these are somewhat larger than the Z4’s single opening. Standard Xenon headlights with auto-leveling include BMW’s popular luminous rings on the inboard lamps, functioning as parking lights but also remaining illuminated when the headlights are on. A high-intensity headlight cleaning system is also standard.

As on Z4s, the hood is aluminum, positively influencing weight distribution and overall vehicle weight; it includes two longitudinal “precision lines” not present on Z4s. At the sides, the 18-in. M Double Spoke wheels and their ultra-low-profile performance tires reflect the Roadster’s and Coupe's performance priorities, while an M logo just behind the characteristic Z4 diagonal slash and its BMW logo/turn indicator confirms the Roadster’s and Coupe's heritage.

In its rear view, the Roadster and Coupe have distinctive bumper assemblies; this includes an air diffusor to promote aerodynamic efficiency and cutouts for the four chrome exhaust tips. As on ’08 Z4s, the taillights feature upper sections with three horizontal LED strips; these sections serve the second stage of illumination provided by BMW’s Adaptive Brake Lights under hard braking. The M logo appears again here, on the left side of the trunklid.

The Z4 M Roadster and Coupe interior: M also means luxury
The Z4 M Roadster and Coupe embody the best of Z4 luxury and adds a personalized motorsports touch that only BMW’s M division can provide.

Doorsill trims display the M logo (with its three colors) in a large, handsome format. Once inside the M cockpit, the driver and passenger enjoy a uniquely sporty, high-quality atmosphere blending BMW M’s style of abundant luxury with typical BMW functional design.

Premium Napa leather M sport seats (choice of manual or power) include embossed M logos on the head restraints. Leather also appears on the door panels, console armpad, kneepads, handbrake grip and shift knob.

Trim materials are special: the largest areas (across the dash, center console) are in a sporty-technical Hexagonal surface, while pearl-gloss galvanic trim appears on the climate controls, interior door handles and pulls, and the “tubes” into which the main instruments are recessed. Automatic climate control is standard in the M, and its rotary knobs also include rubber touch surfaces that enhance their tactile feel.

Tactile feel is also a strong point of the M sport steering wheel, which displays its heritage with an M logo on the bottom spoke and M-color stitching of its thick leather rim. Fingertip audio controls and tilt/telescopic adjustment are included on the wheel.

As in other M models, instrumentation is special, both optically and functionally. The instrument cluster reflect the M’s performance capabilities with special features:
• 9000-rpm tachometer
• Variable tachometer warning segment that lowers redline according to engine temperature: lowest with a cold engine, then increasing in increments to an 8000-rpm limit with a fully warmed-up engine. Although this feature appears in some regular-production BMW models, the BMW M graphics (with an arc of orange and red LEDs) are different.
• Oil-temperature gauge at bottom of tachometer dial
• 180-mph/300 km/h speedometer
• Distinctive graphics throughout, including red-on-gray dial pointers.

Two alternate interior trim materials are offered in place of the standard Hexagon: Carbon Leather or the elegant Madeira Walnut wood, both at no extra cost.

Also available is even more luxurious Extended Leather upholstery; see options for details on this and other available features.

Z4 M Roadster soft top: Fast access to open-air driving
A fully automatic soft top, which comes in a choice of three colors and includes an interior lining for enhanced weather protection, is standard equipment on the Z4 M Roadster.

The rear window is glass, and includes heating. Like the Z4 3.0i and 3.0si, the Z4 M Roadster has a variable storage compartment for the softtop, which allows greater trunk space when the top is up; however, compared to the Z4 Roadster, the M’s trunk has about 3/4 of a cubic foot less volume because its battery and the M Mobility System are carried within the trunk space.

An extensive complement of safety engineering and features
Every current BMW incorporates from-the-wheels-up engineering and technology for active safety – the kind that helps drivers avoid accidents – and passive safety – features that help protect the occupants should an accident happen. The Z4 M Roadster’s and Coupe's handling and braking capabilities, described earlier, are the active side; occupant-protection features include the following and more:
• Dual front-impact Smart Airbags
• Automatic safety-belt tensioners and force limiters
• Seat-occupation detection on passenger’s seat
• LATCH attachment of child-restraint safety seat to passenger’s seat
• Side-impact airbags
• Rollover Protection (Z4 M Roadster)
• Battery Safety Terminal
• Advanced Crash Safety Management (ACSM) for deployment of safety devices and systems.

Options
The Z4 M Roadster’s and Coupe's level of standard equipment is generally higher than that of the respective Z4 3.0si models; but it does offer an interesting array of options:
Premium Package. Combines luxury and convenience features, plus BMW Assist, BMW’s system of customer services and in-car telematics. The Package includes:
• Auto-dimming interior and exterior mirrors
• 8-way power sport seats with driver’s-seat memory (the thigh-support adjustment remains manual)
• Cruise control
• Premium Sound System
• Storage package – elastic net on right side of center console and back of each seat.
• BMW Assist with a 4-year subscription

The Premium Sound System retains the 10-speaker count of the standard system, but is upgraded throughout to a level of performance that will delight those who appreciate audio excellence in automobiles. It features –
• Audiophile-quality speakers throughout, including two 160-mm subwoofers incorporating Carver long-stroke technology
• A powerful Carver amplifier and 7-band Digital Sound Processing
• An FM reception-enhancing diversity antenna system.

The Z4 Series was the first European cars to win the coveted THX Certification for their Premium Sound Systems. THX Ltd. was established in 1983 by filmmaker George Lucas, and has taken its mix of technology and certification programs to emerging entertainment media, including home theater systems, DVDs, video games and high-performance automotive audio systems. THX engineers worked closely with BMW to analyze Z4 models’ cabin acoustics, speakers and other audio components to determine whether they perform to THX standards. They did; the result is a THX Certified Premium Sound System that is designed to deliver a music experience as the artist intended.

Metallic paint. Z4 M Roadster and Coupe metallics include Interlagos Blue, Titanium Silver, Black Sapphire, Sepang Bronze, Monaco Blue and for 2008, Space Gray.

BMW On-board Navigation System with DVD database. As in every Z4, the system’s display is housed in a pop-up pod at dash center; in addition to GPS Navigation, On-board Computer and other functions, it also assumes the role of audio-system display. When the radio is switched on, the Navigation monitor automatically rises into its operating position. With the premium audio system (Premium Package), the Digital Sound Processing function is controlled from the Navigation display as well.

Extended Leather upholstery. Although the standard interior (described earlier) is quite luxurious, BMW M offers additional luxury and distinction via this option. Available in Black and Sepang Bronze, it adds leather coverage in many areas:
• Complete door panels; standard coverage is a portion of the doors
• Windshield frame
• Sun visors
• Center console
• Rollover bars.

Alternate interior trim. Choice of Carbon Leather at no extra cost or Walnut Madeira wood at extra cost across the instrument panel and on the center console.
Power seats with driver’s-seat memory. In addition to being part of the Premium Package, the 8-way power seats are available as a stand-alone option.
Heated seats. 3-stage, thermostatically controlled heating provides a wide range of adjustability and steady heat under changing temperature conditions.
Hardtop preparation. Factory preparation for a hardtop installation is a factory option; the removable hardtop itself, of course for the Roadster, is available as an accessory from the BMW center.
HD Radio with multicasting reception capability. This feature not only improves the sound quality of AM and FM stations, but allows access to additional radio programming as well. No subscription fee is needed.