Due to their beneficial effect on environment, electric vehicles are an important factor for the improvement of urban traffic and, more particularly, for a healthier living environment. A particularly promising field of application is the hybrid-electric city bus, which offers unprecedented opportunities for reducing energy consumption and emissions. Nowadays, various hybrid bus configurations are being proposed and are being demonstrated in several European cities with the support of the European Union＇s ＇Thermie＇ programme. The most important hybrid bus project within Thermie is the Sagittaire project [EU Thermie Project Sagittaire, Newsletter 2, September 1998; EU Thremie project Sagittaire, unpublished documents], aiming to introduce hybrid buses in nine European cities: Luxembourg, Besancon, Alicante, Sintra, Stavanger, Trento, Savona, Athens and Bruges.