BMW EfficientDynamics in the BMW Z4 Roadster.

The BMW Z4 comes with all the benefits of the BMW EfficientDynamics technology package as standard. It incorporates numerous functions which reduce emissions and improve fuel consumption, while at the same time boosting performance.
These include innovations such as the Brake Energy Regeneration, the Automatic Start/Stop function or the Electric Power Steering. They all help you take bends and straights with equal relish, without wasting precious energy.

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The Electric Power Steering only activates when it’s needed: when you’re turning the wheel. The energy it requires has previously been extracted by Brake Energy Regeneration from the braking and kinetic energy.
This element of BMW EfficientDynamics replaces the conventional hydraulic power-steering system with an electric motor. While hydraulic systems constantly draw power from the engine – thereby consuming extra fuel – the innovative BMW system only springs into action when it’s actually needed. If you don’t move the steering wheel (on a straight, for example, or on a steady curve) the electric motor remains inactive, reducing power consumption.


Until now, braking had meant giving away energy. Brake Energy Regeneration puts an end to this by using energy gained during braking to charge the battery.
As soon as you release the accelerator or apply the brake, Brake Energy Regeneration uses the energy liberated to charge the battery. This unburdens the engine and reduces emissions.
The targeted generation of electrical energy also has another advantage: At full acceleration, the engine also has the propulsive force at its disposal that would otherwise be channelled off to charge the battery in conventional systems. The result is an increase in not only cost-efficiency but also driving fun.


The most dynamic and comfortable way to save: the only 8-speed Steptronic Sport transmission in the BMW Z4 not only ensures incredibly soft changes and reduces background noise at high speeds, but also significantly reduces fuel consumption.
Only the rev counter will reveal how swiftly and comfortably the 8-speed Steptronic Sport transmission changes gear. The individual gears are finely graduated so that the change takes place with small rev intervals and the transmission process itself is barely perceptible. At the same time, the engine is always held at the performance level that allows it to make optimum use of its strength and efficiency.
At high speeds the engine revs drop due to the additional gears, thus decreasing fuel consumption and also engine noise. The system is assisted by the newly developed and more efficient converter clutch – even if you use the electronic gearshift lever to change gear manually.


Red lights, traffic jams, road works – in everyday driving situations there are countless instances where the engine is idling, unnecessarily burning fuel. The Automatic Start/Stop function in the BMW Z4 switches off the engine when the vehicle stops temporarily and thus avoids unnecessary fuel consumption.
The Automatic Start/Stop function in the BMW Z4 (sDrive18i, sDrive20i and sDrive28i) switches off the engine as soon as the vehicle is not moving and the driver disengages the clutch (for manual transmission) or operates the brake (for Steptronic transmissions). However, intelligent electronics only switch off the engine when no energy is needed by other loads and there is no adverse effect on your safety and travelling comfort. For example, the engine remains active until the optimum running temperature has been attained or until the interior climate has reached the desired range. Depending on the type of transmission in the vehicle, when the engine has been switched off by the Automatic Start/Stop function, either releasing the brake or engaging the clutch will cause it to start up again automatically in a fraction of a second. The result is less fuel consumption and fewer emissions.