(Recasts, adds administration review, auto product plans)

LOS ANGELES, Nov 15 (Reuters) - A U.S. appeals court on Thursday dealt another setback to the Bush administration and the auto industry on fuel efficiency by ordering new standards for sport utility vehicles, pickups and other light trucks.

The 9th U.S. Circuit Court of Appeals in San Francisco said the Transportation Department's National Highway Traffic Safety Administration (NHTSA) failed in a 2006 regulation to account for the environmental impact of tailpipe emissions.

The three-judge panel also said the government must close a loophole that permits the vehicle class to satisfy lower fuel efficiency standards than cars.

Environmental and consumer groups who joined several states and others in challenging the regulation called the decision "a stinging rebuke" of the Bush administration's approach for making vehicles run more efficiently in an era of skyrocketing gas prices and concerns about energy security.

NHTSA had no comment and referred calls to the Justice Department, which could appeal to the full 9th Circuit or take other steps.

"It's currently under review and we're considering our options," Justice Department spokesman Charles Miller said of the decision.

The ruling represented the latest legal jolt for the administration and the industry on the issue of emissions standards and fuel economy.

The practical impact of the 9th Circuit ruling was unclear. The court requested new standards be written as "expeditiously as possible" and cover the earliest model year practicable.

Product plans for most model-year 2011 vehicles are already in place and car makers are designing their 2012 vehicles.

"It would be very difficult for manufacturers to change gears, so to speak, in midstream and comply with new standards," said Charles Territo, spokesman for the industry's top trade group, the Alliance of Automobile Manufacturers.

Light trucks represent more than half of sales in the U.S. market and have traditionally been the most profitable for automakers.

In 2006, NHTSA required light trucks to get 24 miles per gallon by 2011, an increase of less than 2 mpg over 2007 models. The were no changes for sedans, compacts and wagons, which must still meet the 27.5 mpg test in place for nearly two decades.

Consumer and environmental groups said the appeals court decision, if it stood, could put pressure on the administration and Congress to act soon on available opportunities to boost fuel efficiency.

"This ruling is for the future," said Joan Claybrook, president of consumer group Public Citizen -- a party to the case.

The administration, after a Supreme Court decision in April that forced its hand, is considering whether to grant California a waiver from environmental regulations to set its own fuel efficiency standards to reduce greenhouse gasses.

Congress could provide clarity on its own by approving new car and truck fuel standards as part of energy legislation. The leading proposal, a Senate plan, would sharply boost fuel economy to 35 mpg by 2020 to cut oil imports and tailpipe emissions.

The Senate bill would address a key concern of the 9th Circuit by removing separate criteria that permit light trucks to achieve weaker fuel economy than cars.

Manufacturers are lobbying for a weaker approach.

Claybrook, a former NHTSA administrator, said automakers could take small steps to improve gas mileage without design changes beyond the 2008-09 time frame. But she pointed out the administration may not be able to write a new rule in time, even if it started now, because its term ends in January 2009. (Reporting by Gina Keating, with additional reporting by John Crawley in Washington D.C.; Editing by Gary Hill and Braden Reddall)

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