[A Formerly Proud Canadian]

Buses are bigger than this CNG powered car that has been available to the general public in the US since 2011 and to fleets since 1998, or any of these vehicles that run on CNG. And how much bigger are the CNG tanks on a bus versus a car? Yet they are safer than compressed air tanks apparently!

[E. Pluribus Unum]

Do you have any operational cost info on them?

This is not new technology. It's been around as long as cars have been around. If it were a better idea, it would have been done already.