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The BMW Z4 3.0si and M Coupé
1. The BMW Z4 3.0si and M Coupé 3
2. Short Story 5
Design - a ‘Pocket GT’ 5
Front, back and sides 5
High-performance Drivetrain 7
Z4 M Coupé 7
Variable M differential 7
Z4 3.0si Coupé – fast and frugal 7
Sport automatic gearbox 9
Rigid yet lightweight body and CSL suspension 9
CSL inspiration 9
Class-leading safety systems 11
Enthusiasts’ market 13
A niche market for exclusive customers 15
Limited history 15
BMW Concept Coupé Mille Miglia 17
BMW’s ninth brand-new model in three years* goes on sale in August. BMW designers and engineers have recreated an exciting derivative seen only twice in the last 65 years - the roadster-based coupé.
In the words of Adrian van Hooydonk, Head of BMW Brand Design, “the new BMW Z4 Coupé is best described as a Pocket GT”. The car has been designed to feel ‘shrink-wrapped’ around its components and occupants to create the tightest-packaged high-performance long-distance GT car possible.
The new BMW Z4 Coupé was developed as an ‘unofficial’ special project by BMW’s design team during the development process of the Z4 Roadster. Once the Coupé got the green light for production in 2005, it was then a relatively simple task to integrate it with the underpinnings of the new Roadster. The Z4’s dynamic chassis and unique engine technology combine successfully with the new Coupé package. The addition of the Coupé’s exceptionally rigid body shell ensures that the new fixed-head offers unsurpassed levels of traction and agility for the ‘ultimate’ driving experience.
*From the summer of 2003, BMW has launched brand-new derivatives of 1 Series, 3 Series Saloon, 3 Series Touring, 5 Series Saloon, 5 Series Touring, 6 Series Coupé, 6 Series Convertible and X3
“The new BMW Z4 Coupé is best described as a Pocket GT,” said Adrian van Hooydonk, Head of BMW Brand Design. “The Z4 Coupé should be considered as a fully fledged GT car that has been shrink-wrapped around two people. It represents the smallest possible package that can accommodate the occupants and enough luggage for a long journey while still retaining the strong, muscular stance of the cutting-edge Z4 Roadster.”
“In common with the outgoing Z3, when designing the new Z4 family, we were designing a Roadster for those who appreciate open-topped motoring and the Coupé for customers who want a compact long-distance GT car,” he continued.
“Interestingly, the new Coupé was actually designed at the same time as the original Z4 Roadster in the late 1990s. BMW’s hugely successful launch of new models in recent years left some of the more niche models on the drawing board. But my design team and I pushed for this car and an opportune time to engineer the car for production. Designing the two Z4 models simultaneously ensured that both share a common design theme and a cohesive appearance,” he concluded.
From the front, the only visual difference from the Roadster is the ‘double bubble’ contoured roof. This serves as an aerodynamic aid as well as offering additional headroom to taller occupants. The side view is identical to the profile of the Roadster from the front bumper back to the A-pillar and for the full length of the car below the shoulder line. Above this, the gently sloping Coupé roofline culminates at the rear of the car with a subtle aerodynamic lip spoiler.
From the rear, the Coupé shares the same new rear lamp clusters as those introduced on the Roadster in early 2006. Light conductor rods are fitted, which illuminate a split-second earlier than conventional bulbs. The light units sit on each side of the large clamshell hatchback lid that covers the 340-litre boot – easily enough to stow the luggage for a weekend away.
BMW Motorsport’s Z4 M Coupé takes the Pocket GT design and adds a distinctive sporting edge. A lower front valance with large air intakes dominates the frontal view. The power bulge in the bonnet, created by two sharp front-to-rear crease lines, also highlights the potential of the high-performance M variant. From the rear, similar high performance traits are exhibited. BMW M’s trademark four exhaust tailpipes protrude from an aerodynamic rear diffuser that ensures the car stays firmly planted on the road. In profile, the Z4 M Coupé shares the lightweight five-spoke alloy
wheel design with the Roadster and they clearly display the M3 CSL braking system behind (only on the M derivative).
The launch of the new Z4 Coupé offers UK customers a new BMW engine / model definition. It is the first time that a roadster-based Coupé has been offered with a 3.0-litre engine alongside the high-performance M Coupé derivative. Drivers now have the choice of the lightest production six-cylinder engine in the world powering their Coupé or the seven-times International Engine of the Year category-winning BMW Motorsport powerplant - a focused high-performance model line-up that will whet the appetites of motoring enthusiasts.
The new BMW Z4 M Coupé is powered by BMW’s familiar 3,246cc Motorsport engine. Delivering 343hp at 7,900rpm, it easily surpasses the magical 100hp per litre benchmark for naturally-aspirated high performance engines. Maximum torque of 365Nm is achieved at 4,900rpm and, highlighting the powerplant’s flexibility, 80 per cent is available below 2,000rpm.
Such sporting statistics translate into scintillating performance, with the new Z4 M Coupé posting a zero to 62mph time of 5.0 seconds before going on to an electronically limited top speed of 155mph. These commendable figures do not compromise the economy of the car, with the Coupé delivering a combined fuel consumption of 23.3mpg and recording a CO2 output of 292g/km.
The high levels of power and torque are translated onto the road via a six-speed manual gearbox and BMW’s Variable M differential. Unlike a standard fixed-ratio ‘limited-slip diff’, the Variable M differential delivers a fully variable zero to 100 per cent of available power to the wheel that can most use it in any given situation. It works by using a pump to generate internal pressure when a wheel starts to spin. This pressure is applied to a clutch that transfers power across the rear axle to the wheel with most grip. The result? Lateral cornering acceleration that is higher than is permitted by a conventional differential, a limited slip differential or any form of traction control system.
The ‘entry-level’ Z4 3.0si Coupé offers 265hp at 6,600rpm and peak torque of 315Nm at a relatively low 2,750rpm. These maximum performance levels are assisted by pressing the Sport button located in the centre console. One touch of the button quickens the throttle response as the car accelerates from zero to 62mph in 5.7 seconds and, if left unchecked, travel on to an electronically limited top speed of 155mph. However, this performance is not delivered at the expense of economy - the 3.0si model delivers a combined fuel consumption of 31.7mpg while emitting 213g/km of CO2.
The new BMW Z4 3.0si comes with a six-speed close-ratio manual gearbox as standard. Those drivers preferring the choice of automatic transmission convenience and manual gearbox involvement will choose BMW’s new Sport automatic transmission. Based on a conventional automatic gearbox, a new torque converter and software installation offers a 40 per cent improvement in the gearbox response time compared to a conventional automatic gearbox and a gear change time that is twice as fast.
The Sport automatic system features steering wheel-mounted paddles as a dynamic accompaniment to BMW’s traditional Steptronic gear lever. Finally, in common with the sporting pedigree of the new Coupé, this automatic gearbox will blip the throttle on down changes.
A key aim for the Z4 engineers was to develop a roadster with the stiffest body structure of any open-topped car. Successfully achieved, the Coupé’s foundations were immediately in place and the addition of a fixed roof increased the structural rigidity still further to 32,000Nm/degree. The Z4 Coupé features one of the stiffest body structures of any production car.
And this has not been achieved by the addition of extra weighty bracing. As a consequence, the new Z4 3.0si Coupé weighs just 1,395kgs and the high-performance 3.2-litre M Coupé 1,495kgs – only 10 kilograms more than the Z4 M Roadster.
When the Z4 design team were charged with creating a more sports-oriented car than the Z3, they did have one serious advantage - access to componentry and technology from the inspirational M3 CSL. The new Z4 M Coupé uses the CSL’s 345 x 28mm front and 328 x 20mm rear drilled and vented brake discs and high-performance callipers. Suspension components from the M3 CSL, such as the single-joint front axle with McPherson spring struts, forged aluminium track control arms and separate mountings for the springs and dampers, are also used in the Z4 to offer the highest levels of agility and traction.
The BMW Z4 3.0si Coupé features the electrically assisted Servotronic steering from the Roadster. With its electrical assistance, engine power normally needed to drive a hydraulic steering pump is reduced, equating to a reduction in fuel consumption of one litre per 250 miles. The M division rightly ploughs its own furrow and following many thousands of miles of evaluation on the Nürburgring, engineers from BMW M decided to equip their car with conventional hydraulic assistance. In their expert opinion it offered an even firmer steering feel – perfect for the M experience.
Keeping the high levels of performance firmly connected to the road is the responsibility of the most advanced traction control and stability system available – Dynamic Stability Control +. BMW’s ‘standard’ DSC system maintains traction by reducing engine power, applying the brakes where necessary and monitoring the yaw angle of the car, bringing it back into line whenever needed. DSC+ has five additional features to provide yet further safeguards and comfort for the driver.
However, the laws of physics still apply and should the worst happen, the occupants of the Z4 Coupé are well protected.
BMW’s Advanced Safety Electronics (ASE) system uses remote satellite sensors around the car to control the two front and two side airbags. In the event of an accident, ASE will also separate the battery terminal, deactivate the alternator and switch off the fuel pump to minimise the risk of fire. In addition, the system will open the central locking and illuminate the interior lights and hazard warning lights to warn approaching traffic of the problem.
Customers of cars fitted with BMW’s innovative BMW Assist system (in conjunction with Navigation) benefit from additional peace of mind. In the event of an emergency, occupants can select the Assist feature in the on-board monitor. This opens a telephone call that connects them to the Emergency Services call centre who can dispatch assistance as necessary. Should the car be involved in an accident where the airbags deploy, the car will automatically connect to the call centre. If the call centre receives no response, they will dispatch help to the co-ordinates supplied by the navigation system.
Another safety feature now widely used on BMW cars is Run-flat tyres. Since their introduction, thousands of customers have realised the benefits of these unique tyres. In 2005 alone, it is estimated that approximately 3,000 drivers of Run-flat tyre-equipped BMWs and MINIs in the UK who suffered a puncture were able to get home, or to a dealer, without having to perform a potentially dangerous wheel-change.
The new Z4 3.0si Coupé is equipped with Run-flat tyres that, in the event of a slow puncture or a high-speed blow-out, can continue to be driven for 150 miles at 50mph, while still retaining the benefits of the DSC+ traction control system and ABS brakes. This not only minimises the possibility of loss of control of the car but also reduces weight and removes the inconvenience and danger associated with changing a wheel at the side of the road.
The removal of the spare wheel and associated jacks and tools eliminates approximately 20 kilograms from the rear of the car, lowering the centre of gravity and improving still further the handling characteristics.
During the development of the Z4 M Coupé, engineers from BMW M evaluated the Run-flat and conventional tyres around the infamous Nürburgring. They concluded that the high levels of performance from the M car necessitated the fitment of ‘conventional’ tyres as standard on all Z4 M Coupés. However, to maintain the highest safety levels, the wheels of the Z4 M Coupé are designed to prevent the tyre coming off the wheel, even in the event of a high-speed blow out. Punctures can be sealed using the M Mobility System and, without a spare wheel, the same weight benefit as the Run-flat tyre solution is achieved.
The recent launch of the new Z4 Roadster marked the first time that Z4 had been offered with Sport models. Having proved successful in other BMW model series - 65 per cent of six-cylinder 3 Series and up to 95 per cent of all X5 vehicles being bought as Sport models - the take up of Z4 3.0si Coupé Sport is expected to be approximately 80 per cent. In addition to the SE specification, Sport models feature:
Customers purchasing the Z4 3.0si Coupé can also benefit from BMW’s Service Inclusive pre-paid servicing packages. Owners can select from a three-year / 36,000 miles or five-year / 60,000 mile Service package that covers the cost of all service items, from £430. ‘Service and Maintenance’ coverage can also be purchased for the
same periods. In addition to the Service package, this covers costs associated with replacement brake pads, brake discs, brake sensors, brake fluid, clutch assembly (if worn) and wiper blade rubbers. This level of cover starts at £720.
The new BMW Z4 is sure to have a wide emotional appeal for both sports car and BMW fans. But with only two seats, the car is unlikely to be on the shopping list of the majority of car buyers. It is, quite naturally, a niche model and will be an exclusive sight on British roads. As a result, BMW UK expects to sell approximately 1,000 Z4 Coupés in 2006, of which approximately 200 are expected to be the high-performance M variant.
The typical buyer of the Z4 3.0si and M Coupés will be male, married and aged between 35 and 45 years. Irrespective of these expectations, the owner of a Z4 Coupé will be a driving enthusiast who enjoys the thrill of driving exclusive, high-performance sports cars.
“Most cars in the sporting coupé sector try to be a jack of all trades…..and end up being the master of none,’ said Jim O’Donnell, Managing Director of BMW (UK) Ltd. “The Z4 Coupé is different – it is a focused sports car aimed fairly and squarely at drivers who love driving.”
The Z4 M Coupé, in particular, is an unashamed performance car as much at home on the race track as it is on the road,” he continued. “This is not a car trying to be all things to all men.”
Very few roadster-based Coupés have been produced in BMW’s history. Each car that has made it to production has been produced in very small numbers. The first, the 1940 BMW 328 Mille Miglia Coupé, is arguably BMWs most exclusive car with only two examples ever built, and both of these were for racing. The open-topped 328 was a limited production, high-performance sports car that was adapted for racing. Clothed in aluminium, each racing Coupé weighed less than 650kgs and developed 135bhp at 5,500rpm from the two-litre engine. This made the cars capable of speeds exceeding 130mph – a speed many modern day two-litre cars struggle to attain.
Nearly 60 years passed before a car adopting the same principle arrived for a wider audience in the form of the BMW Z3 Coupé. The Z3 Roadster evolved into a coupé in 1998 and was launched in the UK with BMW M’s 321hp powerplant. Many
European markets offered 2.8i and 3.0i derivatives but, in the UK, M models satisfied purists’ requirements. Combining an engine that delivered over 100bhp per litre with a very rigid yet compliant chassis, the Z3 M Coupé was considered an out-and-out driver’s car. Its rarity and unusual styling gave it a unique place in the hearts’ of sports car aficionados. It was a car many considered to be for those ‘in the know’. In total, 17,815 cars were built before it ceased production in 2002.
The BMW Concept Coupé Mille Miglia connects the success of the 1940 328 Mille Miglia Coupé with the new Z4 Coupé. Unveiled prior to the 2006 Mille Miglia, the concept took pride of place as the entrants were scrutineered before to the event in Brescia, Italy on May 10 2006.
While the styling unashamedly looks to the past, the modern, multi-award winning BMW six-cylinder engine from the Z4 M Coupé powered the car. Modifications were made to the inlet and exhaust systems of the 343 hp unit to give the concept car more of a ‘racing’ sound at both idle and full throttle.
The concept car’s hinged hardtop roof was a reference to the relaxation of the racing car rules when closed vehicles became eligible to race. Similarly, the new Z4 Coupé is derived from the Z4 Roadster soft-top. The concept also benefits from an extremely lightweight chassis, with the aluminium and carbon-fibre reinforced plastic body ‘stretched’ over a lattice frame and painted in ‘fine silver’, a full-gloss paint with extremely fine pigments that recall classic silver race colours.