Given the number of cars being converted to gas, that isn't such a problem, the tanks are pressuirised and have a high pressure valve put on the side of the car.

The conversion costs a couple of thousand, but the Government here subsidises the costs and you get cheaper tax and fuel afterwards.

Obviously the complete conversion is much more labour intensive than a gas conversion, but I would think the tank is the least of the problems.

H2 tanks are very different to LPG tanks. If you used an LPG tank at maximum pressure with H2, you'd only get about 2 miles.

It would also take a long time to fill up an H2 tank properly. Do it quickly and then 30 mins later you'll have lost 15% once the tank cools down.