Prius-Solar-Lapp-01 ...cool project by Canadian engineer Steve Lapp who modified his 2001 Prius by installing solar panels on the roof. It is admitted that the car is still a rough prototype, but so far the fuel economy improvement are of 10%, a respectable figure; for reference, Honda completely redesigned the Honda Civic engine for the 2006 model and achieved a 6% increase in fuel economy… Link.