cartechboy writes: As car manufacturers battle over futuristic announcements of when autonomous cars will (allegedly) be sold, they are also starting to more seriously put self-driving technology to the test. Earlier this week several Japanese dignitaries drove — make that rode along — as an autonomous Nissan Leaf prototype completed its first public highway test near Tokyo. The Nissan Leaf electric car successfully negotiated a section of the Sagami Expressway southwest of Tokyo, with a local Governor and Nissan Vice Chairman Toshiyuki Shiga onboard. The test drive reached speeds of 50 mph and took place entirely automatically, though it was carried out with the cooperation of local authorities, who no doubt cleared traffic to make the test a little easier. Nissan has already stated its intent to offer a fully autonomous car for sale by 2020.