It might be different from state to state, but this is some info I found.
Before the law was amended to include hybrids, HOV lanes were reserved for cars with two or more passengers during rush hour traffic: 6-9 a.m. weekdays for inbound traffic and 3-6 p.m. for outbound. Motorcycle riders are the only other solo occupants allowed in HOV lanes.
Before the law was amended to include hybrids, HOV lanes were reserved for cars with two or more passengers during rush hour traffic: 6-9 a.m. weekdays for inbound traffic and 3-6 p.m. for outbound. Motorcycle riders are the only other solo occupants allowed in HOV lanes.