The motto of the US state of New Hampshire is “Live Free or Die”. Appropriately enough, NH is currently the only US state offering legal certification for flying cars. But while such a vehicle sounds like a figment of science fiction, it could soon become perfectly normal technology.

       A month ago, the Slovak company Klein Vision tested its AirCar prototype 1 with a 35-minute flight between Nitra and Bratislava airports. The AirCar’s 160 bhp BMW engine can take it up to 2,500 metres, propelling it through the air at 190 kmph for round trips of 1,000 km. Once it lands, it ...