It seems the Prius has found a weekness in the emissions control tests in at least one state.
Every Toyota Prius tested has failed the state of Georgia’s emissions test because the vehicle is required to idle its engine during the test. The Toyota Prius shuts off its engine instead of idling, so the automated test instantly fails the hybrid car.
This presumably affects any car with an engine stop function at idle. It’s just now been discovered because the 2004 model of Prius’ exposing this are just now being required to go through the test to be re-registered.