DETROIT -- Toyota Motor Corp. sells more hybrid vehicles than any other automaker, but an environmental group is targeting the company anyway, saying the average fuel economy of Toyota vehicles is worse than it was 20 years ago.

San Francisco-based Bluewater Network, which advocates government action to reduce dependence on fossil fuels, plans to run newspaper ads this week with the headline, "Is Toyota a Wolf in Sheep's Clothing?" The ads feature a photograph of Toyota President Katsuaki Watanabe alongside a wolf in a business suit.

Bluewater Network says Toyota belongs to organizations that are suing California over its new smog regulations. It also says Toyota's vehicles are becoming less fuel efficient. According to a recent report by the U.S. Environmental Protection Agency, the average fuel economy for Toyota's fleet was 30 miles per gallon in 1985 and is 27.5 miles per gallon this year.

"Is this the same company that brought us the hybrid Prius, claiming to be an environmental leader?" the ad asks.

Bluewater Network took on Ford Motor Co. in 2003 after the automaker reneged on a promise to increase the fuel economy of its vehicles by 25 percent. But this is the first time Toyota has been a target of similar ads. Toyota spokeswoman Nancy Hubbell said the automaker was surprised and disappointed.

"We certainly think of ourselves as an environmental leader," Hubbell said.

Hubbell acknowledged Toyota's average fuel economy has fallen in the last 20 years, but she said that's because the mix of vehicles has changed and now includes trucks and sport utility vehicles.

"Toyota's line of vehicles has definitely changed, but that's based on consumer preferences," Hubbell said.

Hubbell said Toyota does belong to two alliances that are suing California over its new standards. But she said that's because Toyota wants the federal government -- not states -- to pass tough new national standards.

Danielle Fugere of the Bluewater Network said Toyota should simply adopt California's tougher standards instead of fighting them, especially since 10 other states are considering adopting those standards.

Toyota has said it wants hybrids to make up 25 percent of its U.S. sales by early in the next decade, up from around 3 percent of its sales last year. In addition to its Prius hybrid, Toyota has two hybrid SUVs on the market and plans to add hybrid systems to the Camry and Lexus GS sedans next year.

Fugere also criticized Toyota's hybrid SUVs, the Highlander Hybrid and the Lexus RX400h, saying their fuel economy isn't much better than their non-hybrid counterparts. Toyota says the mileage is still better than many passenger cars.

"We think that misleads the public who believe hybrid technology comes with a fuel efficiency increase," Fugere said. "Toyota is not fulfilling its promise."

John Barker, president of New York-based DZP Marketing, questioned Bluewater Network's strategy and said the ads will likely have little impact.

"By inexplicably taking on one of the acknowledged leaders of the environmental movement, they discredit themselves and their cause," Barker said.