automobile using air as fuel

So much for hybrids, electric and hydrogen cars. Maybe compressed air fueled cars is the  future.
It first appeared on BBC January 2008.
One review since then.
Apparently, this car has been in development since 2002. 


Wikipedia has a very comprehensive review of the potential ... very poor at this time.


My question is, if there is potential, why has little progress been made to-date???


I will update this post, if more positive information becomes available.