Thanks to a completely new generation of engines and the sophisticated exhaust treatment system, the emissions are almost undetectable and thus another step forward in the development of diesel technology. "The premise when developing the new Citaro was to combine frugality and economy with an increase in output, safety and comfort at the same time," stresses Hartmut Schick, Head of Daimler Buses. At the heart of the "economic miracle" from Mercedes-Benz is the newly-developed BlueEfficiency Power engine series, consisting of the OM 936 six-in-line-cylinder engine with displacement of 7.7 litres and the OM 470 with 10.7 litres displacement. Both engines comply with the Euro VI emission level as standard and stand out for their longevity, low fuel, oil and AdBlue consumption. These technical innovations have neither made the Citaro heavier nor have they restricted the space available. The innovative 24-volt recuperation module also helps with economy: Electricity, which is produced at no cost by the alternator while decelerating, is stored in double-layer capacitors known as supercaps and used to provide energy when the bus is accelerating. Furthermore, the low-level rear-entry doors help to reduce energy consumption. The Citaro saves between three and five percent on fuel in total. That is equivalent to some 1000 litres of diesel or 2.6 tonnes of CO2 per year on typical mileage. The diesel particulate filters only need to be serviced every two years or after 120,000 kilometres.