Here's the Ontario info:
High Occupancy Vehicle (HOV) lanes
and an excerpt:
Who can use HOV lanes
You can use an HOV lane if you have
at least two people (including the driver) in a:
- car
- van or light truck
- commercial truck less than 6.5 metres long with a gross weight of 4,500 kg or less
- vehicle towing a trailer with a combined vehicle-trailer length of less than 6.5 metres
Some vehicles can use HOV lanes at all times, regardless of how many passengers they are carrying, including:
Some HOV lanes on the Queen Elizabeth Way (QEW), Highway 410 and Highway 403 can also be used by solo drivers with a High Occupancy Toll (HOT) lane permit as part of
Ontario’s HOT lanes pilot program.
You can face fines and demerit points for using HOV lanes improperly.