For at least a decade, a car theft trick known as a “relay attack” has been the modern equivalent of hot-wiring: a cheap and relatively easy technique to steal hundreds of models of vehicles. A more recent upgrade to the radio protocol in cars' keyless entry systems known as ultra-wideband communications, rolled out to some high-end cars including the latest Tesla Model 3, has been heralded as the fix for that ubiquitous form of grand theft auto. But when one group of Chinese researchers actuall...