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Z4 - E89 (2008 - ...) - Drivetrain: Straight-Six in the Roadster

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Z4 - E89 (2008 - ...)
Design and Technology
Design: Modern, Emotional, Authentic
The Retractable Hardtop
Drivetrain: Straight-Six in the Roadster
Body and Safety
Equipment: Driving Pleasure All the Way
Flexible Production
Specifications
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Drivetrain: Straight-Six in the Roadster – the Perfect Team.
- Choice of three straight-six power units.
- 225 kW/306 hp top-of-the-range engine with Twin Turbo and High Precision Injection.
- Sports automatic with double clutch and gearshift paddles on the steering wheel as an option on the top-end BMW Z4 sDrive35i.

The new BMW Z4 offers ideal opportunities to enjoy the sporting side of life – opportunities also borne out by the drive units available for BMW’s new Roadster.
Offering outstanding refinement and superior power combined with supreme elasticity and free-revving driving characteristics, the engines available for the new BMW Z4 come with all the qualities so typical of a BMW straight-six. Indeed, the new BMW Z4 is available with no less than three six-cylinders right from the start, ranging in output from 150 kW/204 hp in the BMW Z4 sDrive23i through 190 kW/258 hp in the BMW Z4 sDrive30i all the way to 225 kW/306 hp in the BMW Z4 sDrive35i. In comparison with other models in the same performance range, both the BMW Z4 sDrive35i and the BMW Z4 sDrive30i offer the fastest and most dynamic acceleration in their class.
Yet a further significant point is that all engines in the range guarantee absolutely outstanding efficiency, BMW Efficient Dynamics ensuring a particularly good balance of driving dynamics, on the one hand, and low fuel consumption and emissions, on the other, in the new BMW Z4.
These special technologies include Brake Energy Regeneration, electro­mechanical power steering, tyres with reduced roll resistance, a gearshift point indicator on cars with a manual gearbox, consistent lightweight engineering, on-demand control of the engine’s ancillaries, a map-controlled oil pump, and optimised aerodynamics. So it virtually goes without saying that all engines available for the new BMW Z4 fulfil the EU 5 emission standard.

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Twin Turbo and High Precision Injection for maximum performance with supreme efficiency.
The top-of-the-range BMW Z4 sDrive35i features BMW’s straight-six with Twin Turbo technology, High Precision Injection and an all-aluminium crankcase already lauded twice as the Engine of the Year. Displacing 3.0 litres, this truly supreme engine offers maximum output of 225 kW/306 hp at an engine speed of 5,800 rpm. In particular, it provides the same torque and power otherwise only offered by a much larger eight-cylinder, but in this case on far lower weight and with far lower fuel consumption and emissions.
Peak torque of 400 Newton-metres/295 lb-ft is ensured by two relatively small turbochargers building up such unique muscle without any noticeable delay and maintaining this high torque level throughout a broad speed range from 1,300–5,000 rpm. As a result, the BMW Z4 sDrive35i accelerates to 100 km/h in just 5.2 seconds (and in only 5.1 seconds with the car’s seven-speed sports automatic with its double-clutch gearbox). This supreme performance then continues all the way to 250 km/h or 155 mph, where electronic control limits the top speed of the car.
High Precision Injection plays a key role in saving fuel to the greatest possible extent. Injecting fuel directly into the combustion chamber, High Precision Injection creates a cooling effect which allows a higher compression ratio and optimises the efficiency of the combustion process.
This second generation of direct gasoline injection developed by BMW ensures a significant improvement of fuel economy without having to make any concessions in the dynamic qualities of the engine. A further point is that the turbochargers, through their concept alone, also help to reduce fuel consumption: With the turbines made of special steel highly resistant to high temperatures and thus able to withstand temperatures of up to 1,050 °C or 1,922 °F, there is no need to increase the supply of fuel in order to obtain an additional cooling effect.
This ensures significant advantages in fuel economy particularly under full load, the BMW Z4 sDrive35i making do with average fuel consumption of 9.4 litres/100 kilometres (equal to 29.7 mpg imp) in the EU test cycle.

Six-cylinder normal-aspiration engines: powerful and light thanks to the use of magnesium.
The two six-cylinder normal-aspiration power units also available in the new BMW Z4 offer spontaneous development of power and performance, excellent refinement and maximum efficiency in their performance class. Displacement is 3.0 litres on the BMW Z4 sDrive30i and, respectively, 2.5 litres on the BMW Z4 sDrive23i. Weighing just 161 kg (355 lb) and, respectively, 158.5 kg (349.5 lb), both drive units, benefiting from their composite magnesium/aluminium crankcase, cylinder head covers made of a special synthetic material and lightweight camshafts with VANOS units made of aluminium, are exceptionally light.
Fully variable VALVETRONIC valve management including double-VANOS on the two six-cylinder normal-aspiration engines is another technology ­developed by BMW, applied successfully worldwide and consistently enhanced to increase the efficiency of the engine. VALVETRONIC controls valve stroke on the intake valves and double-VANOS masterminds the intake and exhaust valve angles infinitely in the interest of maximum flexibility. As a result, there is no need for a conventional throttle butterfly still to be found on former engines.
VALVETRONIC reduces the charge cycle phases to a minimum, allowing particularly efficient use of fuel, building up a powerful torque curve, and giving the engine optimum response.

Setting the standard in acceleration and all-round efficiency.
Interacting with the reduction of weight and friction, both VALVETRONIC and double-VANOS give the six-cylinder normal-aspiration power units an unusual standard of sporting performance borne out by greater agility and a direct response to the gas pedal. The driver’s commands on the accelerator are therefore converted precisely and directly into engine power and dynamic acceleration whenever required.
Displacing 3.0 litres, the BMW Z4 sDrive30i develops maximum output of 190 kW/258 hp at an engine speed of 6,600 rpm, the engine continuing to rev up to 7,000 rpm. Peak torque of 310 Newton-metres/228 lb-ft, in turn, comes at an early 2,750 rpm, enabling the BMW Z4 sDrive30i to accelerate to 100 km/h in just 5.8 seconds (with sports automatic: 6.1 seconds) and continue smoothly up to its electronically limited top speed of 250 km/h or 155 mph.
Offering average fuel consumption of 8.5 litres (with sports automatic: 8.3 litres)/100 km in the EU test cycle (equal to 33.2 and, respectively, 34.0 mpg imp) and a CO2 rating of 199 g/km (with sports automatic: 195 g/km), the new BMW Z4 sDrive30i achieves an impressive balance of performance, on the one hand, and fuel economy/emission control, on the other.
Displacing 2.5 litres and otherwise boasting the same technology as the 3.0-litre, the power unit featured in the BMW Z4 sDrive23i opens up the door to BMW Roadster motoring on a high level. Again, this engine offers an unusually positive balance of sporting performance and superior efficiency, achieving its maximum output of 150 kW/204 hp at 6,200 rpm and peak torque of 250 Newton-metres/184 lb-ft at a low 2,950 rpm. And like the 30i, the engine’s speed range goes up all the way to 7,000 rpm for maximum flexibility.
The new BMW Z4 sDrive23i also sets the standard in its class in terms of acceleration, reaching 100 km/h in just 6.6 seconds (with sports automatic: 7.3 seconds). Top speed, in turn, is 242 (with sports automatic: 239) km/h, equal to 150 and, respectively, 148 mph.
Offering average fuel consumption of 8.5 (with sports automatic: 8.2) litres/100 kilometres in the EU test cycle (equal to 33.2 and, respectively, 34.4 mpg imp) and a CO2 rating of 199 g/km (with sports automatic: 192 g/km), the new BMW Z4 sDrive23i provides a both dynamic and very efficient entry into the world of BMW Roadster.

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Six-speed gearbox with particularly short gearshift travel.
All versions of the new BMW Z4 come as standard with a six-speed manual gearbox bearing out its sporting character in particular through extremely short and crisp gearshift travel even shorter than on all other current BMW models with a manual gearshift. A further important point is that precise guidance of the gear selector lever with consistent shift forces makes every gearshift a further highlight in the driving experience.
Gearshift quality is further enhanced by optimised synchronisation featuring carbon friction linings. And on all versions of the new BMW Z4 the entire drivetrain and all gear increments are precisely tailored to the performance characteristics of the respective engine.
Compared with the former generation, the newly developed six-speed gearbox featured for the first time in the BMW Z4 is 8 kilos or almost 18 lb lighter than before. Running smoothness and gearshift comfort, in turn, are absolutely supreme. And the reduction of engine speed in sixth gear ensured by the gear increments enhances the car’s running smoothness and refinement at high speeds and at the same time promotes its all-round efficiency.

Sports automatic with double-clutch technology: even greater dynamics and efficiency in the BMW Z4 sDrive35i.
As an option the top model in the new range, the BMW Z4 sDrive35i, is available with newly developed sports automatic featuring double-clutch technology. The result is even faster performance as well as a unique combination of supreme dynamics – even in comparison with the six-speed manual gearbox – and all the comfort features of a BMW automatic transmission.
The seven-speed sports automatic with its double clutch shifts gears without the slightest interruption of drive power and traction, offering the driver the choice of both an automatic and a manual gearshift. The fast and smooth gearchange allows unusually harmonious acceleration and at the same time serves to reduce the car’s fuel consumption and emissions.
A newly designed gearshift lever on the centre console serves to control the sports automatic with maximum comfort, following the same control concept as BMW’s current automatic transmissions: The driver’s commands in choosing the gearshift program or in shifting gears are conveyed with electronic precision, the transmission moving back to its starting point after each movement of the lever.
As an alternative the driver is also able to shift gears manually via pedals on the steering wheel. And moving to program D, the driver can shift directly to the manual gearshift mode easily and conveniently at any time simply by pushing one of the paddles.
Again featured as standard, Dynamic Drive Control masterminds several parameters in the car’s overall set-up as well as the gearshift characteristics of BMW’s sports automatic. As a result, the gearshift is even more sporting and dynamic in the SPORT and SPORT+ modes, the manual sports automatic gearshift program thus offering noticeably more dynamic acceleration with an even faster gearshift.
Gears are shifted by closing the clutch even more quickly and giving the driver appropriate sporting feedback. This immediate response is confirmed by the spontaneous movement of the speed indicator in the rev counter again proving the car’s particularly dynamic power and performance.
Sports automatic with its double clutch combines two transmission units in one, offering a total of seven gears. These gears are operated by a ­multiple-disc clutch, the next gear always being pre-selected in the currently inactive transmission unit to ensure spontaneous acceleration without the slightest interruption of traction and power. Close gear increments and the small gear spread of just 4.8 offers the optimum transmission ratio in every situation and under all conditions. To further enhance the degree of efficiency, oil is supplied by a combination of dry sump and injection lubrication.
These features alone ensure an ongoing, consistent surge of power with outstanding acceleration, supreme gearshift comfort and enhanced efficiency.
The BMW Z4 sDrive35i with sports automatic accelerates to 100 km/h in just 5.1 seconds, 0.1 seconds faster than its counterpart with manual gearbox. Average fuel consumption, in turn, is 9.0 litres/100 km or 31.4 mpg imp, down by 0.4 litres/100 km or approximately 5 per cent versus the corresponding model with its six-speed manual gearbox featured as standard.

Further refined: six-speed sports automatic in the BMW Z4 sDrive30i and the BMW Z4 sDrive23i.
Both the BMW Z4 sDrive30i and the BMW Z4 sDrive23i are available as an option with BMW’s six-speed sports automatic enhancing not only the standard of motoring comfort, but also the sporting performance of the BMW Roadster. Indeed, the sporting characteristics of the car are attributable in particular to the direct connection to the engine, closing the transmission immediately after setting off. This, in turn, is made possible by highly advanced torque converter technology with an integrated torsion damper avoiding unnecessary slip and any loss of power.
The result is a driving experience quite comparable in character to the flow of power with a manual gearbox, each movement of the gas pedal being converted spontaneously into powerful action, with response and gearshift times reduced to a minimum.
Shifting back more than one gear is also very fast, not requiring any additional time thanks to the direct changeover to the appropriate gear lane. So through its precise control and minimum converter slip, the six-speed sports automatic also enhances the all-round economy of the BMW Z4 Roadster.
The Steptronic function on the sports automatic transmission gives the driver the option to shift gears manually. Apart from the gearshift lever on the centre console, paddles on the steering wheel are also available for this purpose on the six-speed sports automatic model.
To activate the manual gearshift mode, the driver either moves the selector lever in the appropriate gearshift lane or, from driving program D, simply presses one of the paddles for an immediate gearshift.
The gearshift characteristics of BMW’s six-speed sports automatic are also influenced by Dynamic Drive Control, offering an even more spontaneous gearshift in the SPORT and SPORT+ modes.



Last Updated on Monday, 12 April 2010 14:38  

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