All set for Euro VI: start of series production for the cleanest regular-service diesel bus

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A new chapter in the history of regular-service bus operations: the first series-production Citaro to meet the Euro VI emissions standard left the production line at the EvoBus plant in Mannheim today. With the start of series production, Mercedes-Benz once more takes the lead in the field of eco-friendly buses. Based on pioneering diesel technology, they reduce CO2 emissions and ensure a clean environment for our towns and cities. "In anticipation of Euro VI, we are launching a clean urban bus which provides an affordable means of promoting widespread environmental practice among transport operators," says Hartmut Schick, head of Daimler Buses. The company has already supplied its first touring coaches with Euro VI in the form of the Travego Edition 1.

A true feat of engineering: technology saves 1 000 litres of diesel per year

One of the inherent features of Euro VI emissions technology is that it increases fuel consumption. And yet the Mercedes-Benz Citaro manages to use even less than ever. To achieve this, the engineers have really put their innovative thinking caps on. As just one example: during braking or coasting down a slope, the alternators generate "free" electricity that is then stored on board the truck in a series of super-condensers.

A second example: the rear door entrances are now lower. When "kneeling" or lifting again at a bus stop, the bus therefore requires less energy. All in all, the Citaro with Euro VI saves around three to five percent fuel. With normal service mileage, it will therefore use around 1 000 litres less diesel and emit around 2.6 tonnes less CO2 each year.

New engines with great technical features

Working away at the back of this best-selling regular-service bus are some new engines. The six-cylinder in-line units with a displacement of either 7.7 or 10.7 litres deliver output ranging from 220 to 290 kW (299 to 394 hp). The tried and tested Mercedes-Benz SCR emission control system with AdBlue injection and closed-loop particulate filter is combined here with an exhaust gas recirculation system.

The engines are characterised by a number of special technical highlights. The smaller power unit, for example, is the first diesel engine in the world to feature an adjustable exhaust camshaft. It injects fuel at a pressure of up to 2 400 bar – which is around a thousand times the pressure in a passenger car tyre. The larger six-cylinder engine features the unique X-PULSE injection system with pressure booster.

Citaro: the cleanest regular-service bus with diesel engine

The new Citaro with Euro VI is the cleanest diesel-powered regular service bus. Optimised combustion processes and a complex emission control system reduce the emission of soot particles to just three percent of what was possible 20 years ago with Euro I. Emissions of nitrogen oxides have fallen to five percent.

To accommodate the new engines and the complexities of the emission control system, the Citaro now features a new tail end design. The potential extra weight of Euro VI is compensated for here by a number of measures, ranging from a lightweight glass-fibre-reinforced plastic roof to a weight-optimised rear axle. As a result the payload, and thus the number of passengers who can be accommodated in the Citaro, remains unchanged.

The new Citaro is rolling off the production line at the Mannheim plant. EvoBus GmbH produces urban buses, inter-city buses and touring coaches here with a workforce of around 3 500.

Credits: Daimler AG

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