DaimlerChrysler says it will become the first manufacturer to unveil a diesel concept car that will meet more stringent pollution rules and get higher mileage than diesels now on the road.

DaimlerChrysler has not decided whether to manufacture the concept car, which was demonstrated in Landover yesterday and will be unveiled officially in Washington today. But officials of the German company said its diesel technology will be incorporated into future models as a way to meet federal emissions requirements that will take effect in 2007. They said the technology also would meet more strict emissions requirements in California and several other states.

The technology, along with the car's lighter materials and aerodynamic design -- its shape was inspired by a tropical fish -- allows it to achieve about 70 miles per gallon, according to the company.

"This is a highly efficient, super-clean diesel that doesn't have any compromise in performance," said Dennis B. Fitzgibbons, director of public policy for DaimlerChrysler in Washington.

While diesels are popular in Europe, Americans have shown little interest in them. Sales account for less than 1 percent of the market. Manufacturers like DaimlerChrysler that plan to pursue U.S. diesel sales will have to overcome negative perceptions of diesels stoked by cars manufactured in the 1980s that belched black exhaust, made a lot of noise and had no acceleration. The concept car is far different, DaimlerChrysler officials said.

"It's going to have to be something quite special for Americans to purchase diesel," said George C. Peterson, president of AutoPacific Inc., an industry research firm in Tustin, Calif.

The four-seat vehicle, manufactured by the company's Mercedes-Benz division, will be displayed at a DaimlerChrysler symposium at the Washington Convention Center at a time when Congress is considering energy legislation that may include tax incentives for producing and purchasing cleaner-burning diesel cars. Company officials said the car is not being used to lobby for any legislation, though environmental groups said they believe the company would use the car to seek tax breaks.

Many automakers have been trying to figure out how to meet the more stringent diesel pollution requirements. And industry observers said this marks the first time a company is displaying a concept car showing how it would be accomplished. Earlier this year, Ford Motor Co. introduced a Mercury concept car that it said could "potentially" meet the new standards.

The standards are designed to reduce nitrogen oxide and soot that diesel automobiles spew into the air. In Europe, some trucks use a version of the technology. Diesel cars on the market today cannot be sold in California and several other states that have more strict pollution requirements.

Some environmentalists reacted with skepticism to the Daimler car, noting that manufacturers often introduce flashy concept cars that never make it to the production line. They also said the country would be better served by companies making more gasoline hybrid vehicles because they pollute less than cleaner-burning diesels.

"The auto industry is trying to convince the car-buying public . . . to reject better technology like hybrid cars," said Dan Becker, Washington director of the Sierra Club's Global Warming Program.

Herbert Kohler, a DaimlerChrysler vice president who worked on the car, said that for many city drivers the vehicle would achieve higher mileage than gasoline hybrids and that it would not emit much more pollution.

When designing the car, the company looked at different aquatic life to figure out which moved the most efficiently. Designers ultimately settled on a shape that resembles a boxfish. The car, which has sleek lines and a boxy rear, does not look anything like models on the market.

The car uses catalytic converter technology that reduces emissions by taking advantage of lower-sulfur diesel fuel coming onto the market next year. Other pollutants are reduced by treating exhaust with a liquid called urea that drivers will need to refill.

Company officials could not say whether cars with the new technology would cost more than diesels now on the market. The vehicle has not been crash-tested but its designers say it meets U.S. safety requirements.

DaimlerChrysler prototype demonstrated yesterday in Landover promises up to 70 miles a gallon and low emissions without compromising performance.