Most electric vehicles on sale today feature a one-speed transmission, or single reduction gear, that is linked to the electric motor. This setup is both simple and effective given the fact that e-motors are high-revving in nature, are efficient across a wide rpm range, and are capable of producing good torque from low rpm.

However, what if the transmission had more than one gear? Well, ZF has done exactly that, and is showing off its newly developed electric drive unit featuring a two-speed transmission. This is said to improve energy conversion efficiency, which in turn, allows for more driving range.

According to ZF, vehicles with its system (referred to as 2-speed e-drive) consume less energy and provides up to 5% more range. In operation, the system shifts up at 70 km/h, allowing for the shorter gear to be used when setting off, while the taller gear is called into action during instances where brisk acceleration is not needed like when cruising.

The company also explained that efficiency can be further improved by linking to the vehicle’s CAN bus to devise alternative shift strategies. For instance, the vehicle could analyse the GPS route programming in the navigation system to identify how far the next charging station will be, and respond predictively by switching into a more economical driving mode.

Like the electric drive units developed by Tesla and BMW, ZF’s creation integrates the electric motor, transmission and power electronics into a single unit to ensure it’s as compact as possible.

The modular design of the unit also allows e-motors of different outputs to be used, with ZF mentioning (188 hp) 140 kW and 335 hp (250 kW) options. It adds that the two-speed system is suitable for compact passenger cars where interior space can be limited, although it can be fitted to larger vehicles if needed.

The idea of multi-speed transmissions for electric cars isn’t entirely new, as the Tesla Roadster originally came with a two-speed unit, which was later swapped out for a single-speed one due to reliability problems. In motorsport, the first-generation Formula E race cars used five-speed transmissions, while the second-generation cars come with single- or three-speed gearboxes, depending on the team.

On a related note, Kreisel Electric, together with Sala Drive, unveiled an automated two-speed transmission specifically designed for use in electric powertrains last year, which can handle up to 805 hp (600 kW) and an input torque of up to 900 Nm.