A new kind of diesel vehicle — one that runs cleaner, quieter and quicker — will make its San Diego debut this fall, but how big of a splash it makes depends on fickle consumer reaction.

Volkswagen of America Inc. and Mercedes-Benz USA LLC are leading the way in an original era of diesels, introducing the 2009 Jetta BlueTDI and Mercedes-Benz ML320 BlueTec, as early as August.

Miramar Volkswagen San Diego expects to receive its first demo low-emission, diesel-fuel Jetta for test driving before the end of June.

Volkswagen originally promoted the new Jetta’s restricted nitrogen oxide emissions and freeway mileage of 60 miles per gallon of gas, but the newer technology has proven to somewhat diminish the car’s fuel economy. More recent test drives measured the clean-diesel Jetta’s mileage at closer to 40 highway mpg.

Mercedes has received certification for its truck line, and local dealerships expect an early fall release of those vehicles, including the GL620 and ML sport utilities and the R-class van series.

With estimated mileage of 18 city/24 highway mpg, the ML320 BlueTec surpasses its gas-engine counterpart ML350 in fuel economy, the latter with mileage estimated at 15 city/20 highway mpg.

Newer filters in the diesel emissions systems trap the pollutants and process them automatically, thus keeping that matter out of the atmosphere.

Several models, including those from Mercedes and upcoming BMW and Audi versions, will require the maintenance of a 6- to 8-gallon tank of urea, an ammonia-rich solution that neutralizes smog-forming nitrogen oxides.

An estimated base price for the Jetta diesels is $22,000 while the Mercedes diesels start at $46,000.

At a higher price premium and requiring fuel that now costs as much as $5 per gallon, the new diesels have a lot to prove in today’s turbulent economy, though research is showing some offsets to their high costs.

Clayton Cornell is managing editor for GreenOptions.com, one of a network of environmentally focused blogs published by Berkeley-based Green Options Media.

The new clean-diesel vehicles cut carbon dioxide emissions by 90 percent compared to diesel engines of the past, Cornell says.

“California has one of the strictest emission standards in the world, and their low-emission vehicle classification has allowed them entrance into this market,” Cornell said. “Not all gasoline cars are meeting that standard.”