It is certainly not a solved problem. At 300+ bars, just the rupture of a filled tank could cause a significant explosion, even without the hydrogen igniting. I

It is certainly not a solved problem. At 300+ bars, just the rupture of a filled tank could cause a significant explosion, even without the hydrogen igniting. If the hydrogen stored in a car ever catches fire, there will be a very quick reaction. In Norway, they closed down all Hydrogen fuel stations after a minor explosion this year (fortunately the main tanks did not explode).