&gt;Since all these cars passed the laboratory test, that means there must be something very wrong with the test and the way the standards are enforced.<p>It depends how the law is written.<p>Case a) - the cars must <i>never</i> emit more pollutants than specified in these rules - then yes, you are correct. The car manufacturers would be rightly concerned about the wide range of situations they would need to account for.<p>Case b) - the cars must not emit more than the specified amount of pollutants under these specific test conditions (implying hopefully &quot;we understand that the real world performance will differ, and are willing to accept this for the sake of simplicity in testing&#x2F;lawmaking&quot;) - in this case the system is working as intended.<p>I am not sure which case we are dealing with, maybe someone can advise us.