WASHINGTON — When it comes to using car pool lanes, only the most fuel-efficient hybrids need apply.

The government proposed new criteria this week for certifying vehicles as clean and energy efficient — standards for states that let hybrid drivers travel without passengers in the special lanes to avoid rush-hour traffic.

States typically restrict high occupancy vehicle, or HOV, lanes to vehicles with two or more people during designated hours.

For the driver of a hybrid to qualify for HOV lanes during peak time, hybrid vehicles would need to achieve 25 percent higher combined fuel efficiency for city and highway driving compared with similar gasoline-fueled vehicles.

Only four manufacturers — Toyota Motor Corp., Honda Motor Co., Ford Motor Co. and Mazda Motor Corp. — make vehicles that would qualify. A limited number of natural gas vehicles built by Honda and Ford also would meet the standards.

The qualifying vehicles include: the 2004-07 Toyota Prius, 2006-07 Toyota Highlander Hybrid, 2006-07 Lexus RX400h, 2006 Mazda Tribute Hybrid, 2005-07 Ford Escape Hybrid, 2006-07 Mercury Mariner Hybrid, 2003-07 Honda Civic Hybrid, 2003-06 Honda Insight and 2005 and 2007 models of the Honda Accord Hybrid.

Natural gas versions of the 2003-05 Honda Civic and 2003-2004 Ford Crown Victoria would apply, too.

Some of the vehicles that would not qualify include the luxury Lexus GS450h Hybrid, DaimlerChrysler AG's Dodge Ram Hybrid and General Motors Corp.'s Saturn Vue Greenline Hybrid.

Auto industry officials were reviewing the proposal and declined immediate comment.

The proposal unveiled Thursday seeks to balance the government's interest in promoting the fuel-efficient vehicles with concerns that an influx of hybrids could clog up car pool lanes in congested cities.

Most states require HOV lanes to carry two or more occupants. The federal highway bill signed in 2005 allowed an exemption for fuel-efficient vehicles carrying only the driver. The new criteria was developed for the Transportation Department, which administers HOV programs.

Lawmakers in Georgia and Colorado have approved similar plans, and the vehicles can also be used in HOV lanes on a highway on New York's Long Island, said Scott Nathanson, national field director for the Union of Concerned Scientists' clean vehicles program.

Nathanson said the proposal would encourage the "best and the brightest" of the hybrid choices instead of "allowing muscle hybrids or hybrids that are not really using the technology to push the envelope."

Hybrids also could qualify as energy-efficient by achieving 50 percent or better in-city fuel economy. Dedicated alternative fuel vehicles could qualify, too, to use the lanes.