The point here is that under the relentless pressure of the NGOs and other green organisations which seem to wield far more than a democratic influence, limits are set which have no relation to the benefits they will derive nor whether or not they can be achieved. Indeed it seems the real objective is to set limits that cannot be achieved since that is the best way to bring down western society and then remake it in the "New World Order" mould they want.
What this means is that either car manufacturers cheat or they switch to making bicycles.
A UK study (designed to inform policy makers) for the government some time ago reported that nowhere in the UK were particulates above the safe levels except briefly and occasionally in some locations close to major arteries and at peak traffic times.
Of course, the original draft report, written objectively in neutral language that talked about all cause cardiovascular diseases where whole life exposure had some effect on life expectancy, has probably since been published politicised and using emotive language and talking not about a few weeks less life for a few people with a life time exposure but of deaths as if they caught a whiff of cyanide). Note that they are talking about the number of NOX deaths per year and expect this number to increase as the debate heats up exactly as it has done with the "activist scientist" (that modern phenomenon) authored reports on Marine pollution and complete with the obligatory multiple computer models.
There is somewhere a Rockefeller report on trans-boundary migration of pollution and the factors necessary to creating workable treaties which, in the EU and with the EPA, are conspicuously all broken.
Good treaties means getting the consent of all to effective reasonable and affordable agreements that can be veried and enforced.