Ten Mercedes-Benz eCitaro G fully electric articulated buses with the new pure hydrogen “H₂ mode” drive mode will be put into operation by the city bus fleet of Stuttgarter Straßenbahnen AG (SSB) in 2025.
With them, the SSB is giving the starting signal for the construction of an emission-free bus fleet in the bus network of the state capital of Baden-Württemberg. SSB has been a development partner of Daimler Buses for the Mercedes-Benz eCitaro G fuel cell with H₂ mode.
On 14 April 2025, the first of the ten new fuel cell articulated buses with H₂ mode was presented in Stuttgart by Baden-Württemberg’s Minister of Transport Winfried Hermann, Dr Frank Nopper, Chair of the SSB Supervisory Board and Mayor of Stuttgart, and Thomas Moser, Technical Board Member and Spokesperson of the SSB Board of Management. The handover was carried out by Heinz Friedrich, Head of Sales & Service Germany at Daimler Buses, and Carsten Reineck, Public Transport Sales Germany at Daimler Buses.
SSB will no longer be purchasing diesel buses. From 2027, it intends to operate in the city centre of Stuttgart exclusively with emission-free buses, and from 2035 to be climate neutral across the entire Stuttgart bus network.
Long range, significant recuperation benefits, high drive power
With the new H₂ mode operating strategy, the eCitaro G fuel cell electric articulated buses equipped with a hydrogen-based fuel cell as a range extender can be operated exclusively with hydrogen as an energy source in certain operating scenarios. The pure hydrogen drive mode makes them independent of stationary charging processes. This increases their operating radius compared to hybrid or purely electric technologies.
The three-door fuel cell articulated buses of the SSB are characterised by their long range as well as significant recuperation benefits and high drive power. The battery and the fuel cell are also the energy source for the drive system in the “H₂ mode” operating strategy. However, external charging of the batteries on the mains network during stationary phases is no longer necessary, as they are charged by the fuel cell while driving. The fuel cell always operates in the efficient operating range between 20 and a maximum of 40 kW, even in H₂ mode.
Compared to a hydrogen-only vehicle with a small buffer battery, the new eCitaro G fuel cell with H₂ mode is much better at fully and profitably storing in its large batteries the energy recovered by recuperation when braking. This boosts the overall efficiency of the eCitaro G fuel cell with pure hydrogen drive, particularly in urban traffic where braking is frequent, but especially in difficult terrain, such as on uphill gradients like the Stuttgart Weinsteige. Last but not least, the large battery capacity allows high levels of drive power to be utilised over longer distances without the fuel cell having to operate in the inefficient upper power range. The experts from Daimler Buses provided prior advice to the SSB and evaluated the planned routes for the eCitaro G fuel cell in Stuttgart.
The Mercedes-Benz eCitaro G fuel cell vehicles for SSB are equipped with four NMC3 high-voltage battery packs with a total energy capacity of 392 kWh. The compact fuel cell module has a maximum output of 60 kW and is located on the roof of the rear section directly behind the articulation joint. Six hydrogen tanks each with a total capacity of 30 kilogrammes of H₂ are located on the roof of the individual articulated buses.
Attractive and safe: the equipment of the new vehicles of SSB Stuttgart
The eCitaro G fuel cell articulated buses with H₂ mode from the Stuttgart-based SSB are each equipped with 47 City Star Eco passenger seats in attractive blue-yellow fabric covers (plus driver’s seat) and a powerful Thermatronic air conditioning system. In the première vehicle, four seats in the front area, which were designed in striking grey with a red crossbar and the logo of the VfB Stuttgart premiership football team, underline the SSB’s close ties with the sporting representatives from the Baden-Württemberg state capital.
In addition, there are 77 standing spaces, so that up to 124 passengers per bus can be transported at the same time in spacious and comfortable surroundings. The new fuel cell articulated buses with H₂ mode feature all-round LED lighting technology, roll-pitch control and electrohydraulic intelligent eco steering.
Highlights on board the articulated buses are the state-of-the-art safety and assistance systems. These include Sideguard Assist 2 and Frontguard Assist, Traffic Sign Assist, Attention Assist and the tyre pressure monitoring system (TPM). There is also a reversing camera, a video surveillance system with five mini dome cameras and an 8″ TFT LCD colour monitor as well as an accident data recorder.
A manually operated folding ramp on the central entrance door, a large number of double USB sockets in the interior as well as two generously dimensioned special-use areas with storage and leaning areas for wheelchairs and prams round off the equipment of the new eCitaro G fuel cell articulated buses with H₂ mode, which will be used by the SSB in Stuttgart from 2025.
