Mercedes-Benz and the Daimler Group can look back on the longest and most extensive experience worldwide with hybrid buses. Daimler-Benz AG, as it was known at the time, presented the first bus in the world with hybrid drive at the International Motor Show back in 1969.
An eleven-metre long Mercedes-Benz OE 302 was presented as an urban public transit bus. The direct current vehicle engine achieved continuous output of 115 kW (156 hp) and top performance of 150 kW (204 hp) at low speeds. The vehicle motor was supplied from five battery blocks in the underbody with 189 cells, a total operating voltage of 380 volts and a capacity of 91 kWh. This allowed for around 2.5 hours of operation on scheduled service routes. The battery weighed 3.5 t.
In addition, the bus had a four-cylinder diesel engine with 3.8 litres displacement and an output of 48 kW (65 hp). This unit, built in across the tail end, was switched on in the outskirts of the city and ran with a constant rpm to save on fuel. An electric brake was already being used to recover energy.