>the emissions guidelines were being gamed by manufacturers

Not necessarily gamed - the measuring just needs to factor it in. e.g. (Rather anecdotal) I know there are cars programmed to capture emissions in a filter & then automatically clear that when the car reaches high speeds (freeway). Makes sense in a way...you'd rather have the car expelling the crap on the freeway than city center. That mechanism is apparently a big problem here - I live in a place where the cars never reach freeway speed so they keep clogging (so I'm told).