The counties surrounding Nashville have emissions. If it is an obd2 car it is a simple check for codes and they look for something that resembles a catalytic converter. I believe Davidson, Williamson, Sumner, Wilson, Hamilton, and Rutherford are the only counties around this area that do emissions.
I live in Williamson county in Franklin and honestly you find a few snooty folks here, but it is absolutely beautiful. I would love to live in Maury county as there is no emissions and it is about 45 minutes outside of Nashville.