>>Air car:
>>
>>http://www.popularmechanics.com/automotive/new_cars/4217016.html
>
>Can you imagine the explosion if the air tank should get ruptured in a collision?

Not really, air isn't explosive (to differ from "explosive P" (*)). It would be a mess, of course, but I don't think this is in any way more dangerous than driving a tank full of gasoline vapors on a hot day, or a bottle of propane (that thousands of vehicles in Europe use regularly instead of gasoline) or a similar bottle of hydrogen - which are all combustible and explosive.

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(*) The "explosive P" came up this weekend, there was some guy on the radio, explaining the regional differences in pronunciation of consonants. The sentence "I leave a trace of devastated lavatories" came naturally.