Ithought this might happen: according to the Union of Concerned Scientists’ Hybridblog reports that a US federal transportation bill contains provisions that would open up HOV lanes to hybrids.  The problem—not only could that clog HOV lanes (slowing down the buses, carpools and vanpools that depend on them), but the US Congress is trying to lower the bar, letting even low-mileage hybrids into the fast lane:

In the end, the Senate provision would open HOV lanes to vehicles that achieve at least a 50 percent increase in fuel economy in the city or a 25 percent increase in fuel economy in combined city-highway miles over the non-hybrid model, regardless of the number of passengers.  This… opens up a Pandora’s box of potential abuses.  Not to mention the fact that both the House and Senate language do not even consider smog-forming emissions-with hybrids you don’t have to trade off fuel economy and smog, but instead of recognizing this fact, these bills would allow some higher mpg vehicles into HOV lanes despite the fact that they are among the dirtiest vehicles permitted by law (4-10 times dirtier than many of the hybrids on the road today).

Seems to me that opening up HOV lanes to hybrids was a so-so idea to start with.  But it just got a whole lot worse.