At the close of the first day of the seventh World Solar Challenge, Nuna II, the Dutch built favourite, has established a lead of 50 kilometres in the 3000 kilometre car race from Darwin to Adelaide in Australia. Nuna II was developed by the Nuon Solar Team, who are bidding to retain their World Solar Challenge title after winning the event in 2001 with Nuna I. The team, from Delft University of Technology and Erasmus University Rotterdam, hope to average over 100 kilometres per hour for the race, thus beating their current world record of 91.8 kilometres per hour. The rules of the World Solar Challenge are simple: design and build a car capable of travelling the length of the Australian continent using only the power of the Sun. The event is intended as a celebration of education and technical excellence which also draws attention to the importance of sustainable transport In total, 22 teams are vying for the title, including cars from France and Germany. After the first day's racing, second place was occupied by Australian team Aurora 101, closely followed in third place by the Solar Electric Vehicle team from the US. Nuna II itself has been developed with the help of advanced space technology, provided by the European Space Agency's (ESA) technology transfer programme. The solar powered car has a theoretical top speed of 170 kilometres per hour. Its aerodynamic outer shell is made using the latest lightweight reinforced plastics, while the main body is constructed from carbon fibre and aramide, a metal used to build satellites. The vehicle is powered with the same triple-junction gallium arsenide solar cells used on board ESA's SMART-1 Moon satellite, launched earlier this year. Nuna II also uses maximum power point tracking technology to guarantee an optimal balance between power from the battery and power direct from the solar cells.