RATP, the public-owned company that manages most of Paris' public transport system, is currently performing tests using a hybrid
bus outfitted with ultracapacitors. For now, the test buses are passenger-free. The model, called Lion's City Hybrid, is supplied by German manufacturer MAN and the company claims it reduces fuel consumption about 20 to 25 percent. RATP is testing the bus in four different bus lines, which represent four different types of bus lines configurations, from suburban medium-distance routes to frequent stops. The MAN uses the ultracapacitors to store electric energy, which allow enough juice for the bus to start with the engine stopped. The diesel
engine is just used once the bus is running. Besides the fuel savings, the bus reduces noise pollution, something people living close to bus stops are likely to be thankful for.
[Source: Blog en commun