While DaimlerChrysler's Jeep brand is touting its plan to build a Grand Cherokee with a fuel-efficient diesel engine, the automaker quietly ended production of a successful diesel version of its Jeep Liberty SUV for the U.S. market.

The reason? The engine for the compact SUV doesn't meet tougher federal emissions standards that go into effect next year, and Chrysler said it wasn't cost-effective to the replace the engine with a more modern version.

"The emission standards are becoming very stringent, and we weren't able to make a credible business case for a limited production vehicle," Chrysler spokeswoman Dianna Gutierrez told The Detroit News.

Chrysler's move to stop selling the Liberty in the United States comes despite its success. Liberty sales more than doubled expectations of 5,000 units last year.

In addition, Chrysler has strongly supported diesel engines as a more fuel-efficient option for U.S. drivers. Last week, Chrysler CEO Tom LaSorda touted diesel technology at a meeting of Michigan political, business and civic leaders on Mackinac Island.

LaSorda announced Chrysler will roll out a diesel-powered Grand Cherokee SUV in 2007. Mercedes, Chrysler's sibling division in DaimlerChrysler AG, will make the Grand Cherokee engine.

"This doesn't mean that since we're discontinuing the Jeep Liberty diesel that we're not committed to diesel," Gutierrez said.

She declined to say whether Chrysler will eventually market the Liberty with a more modern diesel engine. For 2007, at least, the Liberty will be available only with a gasoline engine.

The diesel Liberty, which is built in Toledo, will still be sold in Europe, where diesels are far more popular and emission regulations are less stringent.

"Our goal was to test (U.S.) consumer interest in a diesel-powered vehicle and, based on the Liberty diesel, it obviously exceeded our expectations," Gutierrez said.

Dealers are eager to get the diesel Grand Cherokee.

Alan Helfman of River Oaks Chrysler-Jeep in Houston sold 30 to 40 Liberty diesels last year.

"It was a good little seller," Helfman said. "But the Grand Cherokee will sell even better. The diesel in the Grand Cherokee will be utopia, especially since it's a Mercedes diesel."

Italy's VM Motori makes the diesel engine for the Liberty.

Chrysler's decision to end diesel Liberty sales in the United States makes sense given the regulatory environment, said Casey Selecman, an automotive analyst with Farmington Hills-based CSM Worldwide Inc.

Volkswagen will temporarily discontinue diesels in the United States and come back with versions that meet the new emissions standards, Selecman said.

"Everybody's waiting for the diesel fuel quality to change over so that they're able to use future emissions equipment that they can't use right now," he said.

Diesel vehicles account for a small portion of U.S. auto sales, but are expected to grow as high gas prices stoke demand for more fuel-efficient vehicles.

In April, J.D. Power and Associates said light-vehicle diesel sales are projected to grow from 3.2 percent of U.S. auto sales in 2005 to more than 10 percent by 2015.

"Everybody's waiting for the diesel fuel quality to change over so that they're able to use future emissions equipment that they can't use right now," he said.