2025-08-13 Milestone reached thanks to retrofit: First electric tour bus type TZ-S eCoach takes to the road in Erding

HEIDENHEIM, GERMANY: Heidenheim-based global technology group Voith and vehicle conversion firm To Zero Electric Vehicles GmbH from Rausdorf/Erfurt were commissioned by longstanding bus company Scharf OHG to retrofit a battery-electric drive to a diesel tour bus – marking the next milestone on the road to more sustainable bus transport. Not just in the public transport realm, as was previously the case, but now in the tour bus sector as well.

This retrofit project is one of the first of its kind in Germany. To Zero took charge of the technical planning and the conversion, while Voith contributed its innovative Voith Electrical Drive System (VEDS). The VEDS is already being used successfully in many new electric vehicles and has won several awards in Europe for its efficiency and sustainability.

In the retrofit, the VEDS replaces the previous diesel engine and gear box. Specifically, this is a powerful electric drive with a cutting-edge design that is specially tailored to the requirements of tour coaches and fits seamlessly into the existing vehicle architecture. The electric motor achieves a peak output of 410 kW (approx. 557 HP) – and thus delivers more power than the original combustion engine.

This power is available instantaneously over the entire speed range, ensuring fast acceleration and safe overtaking on the freeway. “In addition, our VEDS is distinguished by its high efficiency and reliability. These are all properties that have already been proven in other retrofit projects. Just recently, for example, at the Transdev Group in Schwäbisch Hall,” explains Holger Seefelder, Vice President Sales EMEA at Voith.

The battery technology is the second crucial component for a successful retrofit. For example, the converted bus uses a battery pack with a total capacity of 420 kWh. This huge battery storage volume allows a very long range in practice. The battery system consists of several modules installed in the vehicle where the diesel drive train and peripherals were previously located: One part of the battery units migrates to the former engine bay at the rear, another uses some sections of the luggage compartment. “We have optimized the battery pack so that it does not interfere with the passenger space or drastically reduce the volume of luggage that can be carried. This means that the seating and payload remain almost completely intact,” confirms Michael Pfeffer, CEO and founder of To Zero.

Another important aspect is that the existing assistance and safety systems of the TZ-S eCoach electric bus – from ABS and lane keep assistant to emergency braking and turning assistants – remain fully functional after the retrofit. The tour coach therefore continues to meet all statutory provisions, offers the accustomed level of passenger comfort, and provides sufficient range for everyday travel.