The same system also works for electric motorcycles, which were also first developed for the Tour de Sol. Applications The Venturi Astrolab in 2006 was the world's first commercial electro-solar hybrid car, and was originally due to be released in January 2008. In May 2007 a partnership of Canadian companies led by Hymotion altered a Toyota Prius to use solar cells to generate up to 240 watts of electrical power in full sunshine. This is reported as permitting up to 15 km extra range on a sunny summer day while using only the electric motors. An inventor from Michigan, USA built a street legal, licensed, insured, solar charged electric scooter in 2005. It had a top speed controlled at a bit over 30 mph, and used fold-out solar panels to charge the batteries while parked. Auxiliary power Photovoltaic modules are used commercially as auxiliary power units on passenger cars to ventilate the car, reducing the temperature of the passenger compartment while it is parked in the sun. Vehicles such as the 2010 Prius, Aptera 2, Audi A8, and Mazda 929 have had solar sunroof options for ventilation purposes. The area of photovoltaic modules required to power a car with conventional design is too large to be carried on board. A prototype car and trailer has been built called Solar Taxi. According to the website, it is capable of 100 km/day using 6 m2 of standard crystalline silicon cells. Electricity is stored using a nickel/salt battery. A stationary system such as a rooftop solar panel, however, can be used to charge conventional electric vehicles. It is also possible to use solar panels to extend the range of a hybrid or electric car, as incorporated in the Fisker Karma, available as an option on the Chevy Volt, on the hood and roof of "Destiny 2000" modifications of Pontiac Fieros, Italdesign Quaranta, Free Drive EV Solar Bug, and numerous other electric vehicles, both concept and production. In May 2007 a partnership of Canadian companies led by Hymotion added PV cells to a Toyota Prius to extend the range. SEV claims per day from their combined 215 Wh module mounted on the car roof and an additional 3 kWh battery. On 9 June 2008, the German and French presidents announced a plan to offer a credit of 6–8 g/km of CO2 emissions for cars fitted with technologies "not yet taken into consideration during the