The law says you can’t make a device that causes the vehicle to perform well on the test but perform poorly in other routine scenarios. With your example, you’

The law says you can’t make a device that causes the vehicle to perform well on the test but perform poorly in other routine scenarios. With your example, you’d be stuck arguing to a judge that color printing is not a normal part of your device’s operation and therefore your loophole exploitation is legal. Which isn’t going to get anywhere at all. The law is not stupid nor is it evaluated by machines.