The all-new engine generation in conjunction with the complex emission control system takes emissions to their very limit of detectability, thus representing another step in the ongoing advancement of diesel technology. "Our premise in the development of the new Citaro was combining economy and efficiency with corresponding gains in performance, safety and comfort", emphasised Hartmut Schick, Head of Daimler Buses. The beating heart of this "economic miracle" from Mercedes-Benz is represented by the newly developed BlueEfficiency Power engine series, consisting of the six-cylinder in-line units OM 936 with a displacement of 7.7 litres and OM 470 with a displacement of 10.7 litres.. Both engines meet the Euro VI emission standard as a matter of course and are characterised by their durability together with their low consumption of fuel, oil and AdBlue. The technical innovations have neither increased the weight of the Citaro nor reduced its spaciousness. Also helping it to realise economic savings is an innovative 24-volt recuperation module: energy produced without any expense by the alternator during overrun phases is stored in double-layer capacitors, known as supercaps, which the bus can then use as an additional source of energy during the acceleration phase. The lower boarding height at the rear doors also helps to reduce energy consumption. Overall, the Citaro achieves fuel savings of between three and five percent. Given normal usage, this corresponds to a good 1000 litres of diesel or 2.6 tonnes of CO2 per year. Maintenance of the diesel particulate filters now only needs to be undertaken every two years or after every 120,000 kilometres.