Ill-noise requires it only in the Chicagoland and East St. Louis metro areas. Something about big cities and pollution. That’s also where you cannot get non-ethanol gas. It’s an OBD II tattle tale based system which cuts it off at models older than 1996. The older direct measurement systems have been removed.
when I lived in southeastern WI and was forced to emission test my 74 Nova, I simply ran the tank down to about an 1/8 and then put in a whole bottle of gas line antifreeze a block from the testing center...passed easily, then immediately went to the gas station...worked everytime no matter how bad the car was...:)