The last few years have been very kind to electric cars, mostly thanks to the ice-breaking carried out by the Toyota Prius hybrid, and then the runaway success of Tesla's Model S. Despite their surge in popularity, however, one question has never really been answered properly: What exactly is the range of an electric vehicle? Is it really 350 miles as Tesla claims, or is that some kind of miraculous edge-case that can only be obtained if you're coasting down hill with the windows closed on a sunny day?