Even that is not enough. The vehicle itself may emit zero, but just moving on the roads with wheels on the ground will produce emissions, as tyres grind particl

Even that is not enough. The vehicle itself may emit zero, but just moving on the roads with wheels on the ground will produce emissions, as tyres grind particles out of the road and turbulence lifts dust up in the air. Emissions very definitely is not a black-and-white thing.