Do hydrogen-powered cars have any sort of safety measures to prevent large explosions?
They will probably have fuel cutoffs, like gasoline powered cars. However, provided they are kept outdoors, hydrogen leaks are probably less dangerous than gasoline. Leaking, or burning, hydrogen goes straight up and dissipates in the atmosphere almost instantly, so i fire doesn’t tend to spread. Gasoline runs across the floor, meaning any fire spreads out horizontally. Provided that the hydrogen is not trapped, there is no possibility of an explosion. In bulk, hydrogen cannot explode because there is no oxygen. Some underground car parks may have problems – though even these are usually well ventilated. The only increased danger is that burning hydrogen is completely clear so that only the heat-haze shows where the fire is.
