Mercedes introduced new diesel passenger vehicles last year, Volkswagen has plans to do likewise next year and Chrysler, which offers the Jeep Grand Cherokee as a diesel model, may introduce others.

The buying public understands that diesel engines and fuels are a lot cleaner than they were in the ’70s, said Lou Ann Hammond, CEO of Carlist.com, an automotive information service.

When people realize that diesel engines get at least 25 percent better fuel economy than regular gasoline engines, they’ll be even more interested. With some smaller vehicles with diesel engines, the improved fuel economy makes them compare favorably with gas-electric hybrid vehicles.

As a result, sales of diesel passenger vehicles are forecast to rise dramatically, as are sales of hybrids, in the near future.

According to projections from Siemens VDO Automotive, which supplies diesel fuel-injection systems, diesel sales in the United States are expected to reach 867,000 by 2012, compared with 653,000 this year, the overwhelming majority of which are heavy-duty pickup trucks, not passenger vehicles.

Hybrid sales are expected to come in at around 510,000 in 2012, compared with 193,000 this year.

Much of the diesel gain is expected to be in passenger vehicles. Mercedes last year rolled out the R320 CDI and two other diesel-powered SUVs, and offers the E320 car in diesel.

Volkswagen will bring out a new diesel car next year.

Diesel passenger vehicles are much more common in Europe, where nearly half of the vehicles driven are diesels.

Most estimates say that fewer than 3 percent of cars on the road in this country are diesels. High taxes on gasoline helped contribute to diesel’s popularity in Europe. Now, automakers hope that diesel’s widespread availability in this country will help broaden its appeal to car buyers.