It depends where you are. In Ontario, vehicles with green licence plates are permitted in the high-occupancy vehicle (HOV) lane with any number of occupants. Green plates are available for plug-in hybrids and battery electric vehicles.
In B.C., you can apply for a decal that allows you to drive your green vehicle in the high-occupancy toll (HOT) lane.
In Quebec, a green plate allows you to drive in many reserved lanes, but not all (you can check here).