You may see a few solo drivers legally cruising in high-occupancy-vehicle lanes if you live in California or Virginia. Both states now allow hybrids to use the lanes that were originally intended for carpools. There has been some controversy over letting single-occupant hybrids in, as seen in some of the comments from this Autoblog post. But controversy among hybrid owners in California has arisen over the size of the decals the state DMV requires for use of the HOV lanes. This Los Angeles Times article has pictures of the decals and interviews with some of the owners. Both controversies are teapot-size tempests. Motorcycles have long been allowed in HOV lanes because they don't use much gas and have low emissions, which is exactly the reason for letting the hybrids in. As for the stickers, you could make the same complaint about license plates. As they say, driving is a privilege, not a right.