Many car buyers are disappointed upon finding that the mileage ratings listed on window stickers for new vehicles don't match performance on the road.

The true mileage that the vehicles achieve often is 10 to 20 percent less — sometimes even 30 percent less — than those overly optimistic fantasy numbers on the stickers. That's why we've implored the Environmental Protection Agency on previous occasions to update its vehicle testing standards to reflect the realities of today's driving and make those sticker numbers much more accurate.

We're happy to see that the EPA is finally doing just that. The new, more- accurate mileage ratings will be required for 2008 models expected to come out in late 2007.

On Dec. 11, the agency issued new testing procedures that will result in mileage estimates dropping an average of 12 percent for city driving and 8 percent for highway driving for all vehicles. Gas-electric hybrids, although still among the most fuel-efficient vehicles, will see their ratings drop 20 to 30 percent for city driving and 10 to 20 percent for highway driving.

Under longstanding EPA rules, vehicle makers have been allowed to maximize mileage ratings by testing hand-built prototype vehicles on dynamometers in labs.

That method results in artificially high ratings. It doesn't reflect today's increasingly stop-and-go urban driving in congested traffic, the higher speed limits on many of today's roads, the reduced fuel consumption resulting from increased use of air conditioning and other factors that hurt fuel economy.

Consumer Reports magazine, the AARP, the Union of Concerned Scientists and others previously have complained that the EPA ratings are grossly inflated.

The new ratings undoubtedly will disappoint car buyers who see the lower window-sticker ratings when shopping for 2008 models next year. But it's far better that those ratings reflect the truth, and preferable that buyers know up-front what kind of fuel economy to expect. That will be especially important if gas prices jump above $3 a gallon again.

Congress should help ensure that those sticker ratings rise in future years — without any artificial fudging on the numbers — by taking the long-overdue step of raising federal fuel economy standards for vehicle fleets.

As we have previously urged, fleet standards easily could be raised by five to 10 miles per gallon over 10 years based on proven technology. That would be a significant increase over the current average fuel economy of about 24 miles per gallon for cars and light trucks combined. (Light trucks include pickups, sport utility vehicles and minivans.).

Higher fuel-economy standards would be a boost to energy conservation, curb U.S. reliance on foreign oil and help clean the air by reducing polluting tailpipe emissions.

That sounds like a pretty good deal to us.