LA Metro cng buses

Two of the Los Angeles County Metropolitan Transportation Authority (Metro)'s 2,221 compressed natural gas (CNG) buses seen outside the fascinating architecture of the Walt Disney Concert Hall, completed in 2003. Metro also has one electric, and six gasoline-electric hybrid buses.

CNG buses cost about 10 to 15 percent more to operate than standard diesel engine buses, but the value of a cleaner air more than compensates for this (including in healthcare costs).

That isn't Steven Joyce style bean-counter thinking you say, but it's also possible that natural gas costs will stay low while diesel costs will rise in the medium-term, so it could become a bean-counter plus too.  If only NZ's blockheads could think like this...