General Motors quietly is preparing a myth-busting campaign in advance of next year’s U.S. launch of a diesel-powered Chevrolet Cruze.

Central to GM’s message is that today’s diesel engines bear no resemblance to the soot-spewers of decades past. Their stench still is fresh in the noses of many American consumers, and eliminating that lingering odor presents a challenge.

“But it will be a fun one,” Cruze Marketing Manager Mike Weidman tellsWardsAuto.

He likens the pending diesel proliferation to the recent surge in turbocharging, a trend inspired by increasingly strict fuel-economy standards because turbocharging affords engine-downsizing opportunities without compromising performance.

“There was a whole series of (turbocharger) myths,” Weidman recalls. “People thought that it required premium fuel or that there were durability issues or it was just too powerful, things like that.”

Nevertheless, the number of turbocharged engines available in ’11-model U.S.-market passenger cars rose to 18, compared with 14 in model-year ’10, according to WardsAuto data. Correspondingly, they accounted 21.1% of ’11 car volume for a gain of 7.3 percentage points.

Against this backdrop, U.S. light-vehicle fuel economy ticked up 1.7% to 22.7 mpg (10.4 L/100 km) from prior-year’s 22.3 mpg (10.5 L/100 km), the WardsAuto Fuel-Economy Index shows.

Expect similar improvement if diesel-engine penetration hits 10%, as forecast by Tier 1 supplier Bosch, whose stock-in-trade is fuel-delivery technology for diesel engines.

Current U.S. market penetration, which is in the low single digits, is spread across four car brands: Volkswagen, Audi, Mercedes-Benz and BMW. But recent product confirmations promise the addition, by 2014, of a diesel-powered Jeep Grand Cherokee, Porsche Cayenne and an undisclosed Mazda.

Soaring U.S. gasoline prices, expected by many to reach record levels this summer, also could generate increased demand.

GM’s contribution to the diesel’s anticipated growth will not end with the Cruze. GM North America President Mark Reuss has said the all-new Cadillac ATS will feature a diesel engine.

Weidman’s remarks come as the auto maker reveals personnel at its  Powertrain Engineering Development Center in Pontiac, MI, are leveraging the expertise of fellow GM employees at a sister site in Italy.

The Turin facility will benefit from a E20 million ($26.5 million) investment in five new testing benches to evaluate noise, vibration, harshness, output and performance in severe climatic conditions.

“We’re able to put the diesel engines through rigorous testing,” the site’s managing director, Pierpaolo Antonioli, says in a statement. “We’ve pushed these engines in the labs so that the customer can depend on them in real-world driving situations.”

GM has not decided if the Cruze’s diesel engine will be exclusive to a single trim line or available across the nameplate’s range, Weidman says.

The marketing picture appears equally fuzzy when he is asked about the prospect of launching an advertising campaign that is dedicated to the diesel-powered Cruze.

“We are in the process right now of developing our marketing plan,” Weidman says, adding GM expects some bounce from the glut of online information that accompanies product introductions today.

“The consumer base now is so much more informed than they once were,” he says. “They show up at dealerships sometimes knowing more than the sales person they’re talking to. It used to be in the old world of marketing, you relied on print advertising to really get the details across.”

Communication strategies for advanced technology have occupied much of GM’s time in the last year. The Chevrolet Volt extended-range electric vehicle has been plagued by misinformation.

“The hardest thing we have with the Volt is explaining how it works,” Reuss tells WardsAuto. “Once you do it, people say, ‘Geez, that’s pretty cool.’ But getting that word out is really tough.”

Weidman is philosophical about the fuss, comforted by the knowledge that GM sold some 500,000 diesel-powered vehicles last year – 33,000 of which were Cruzes.

“There’s always a pot of gold at the end of the rainbow,” he says. “Eventually, we’ll be able to look back on a conversation like this and chuckle about it.”

– with James M. Amend

emayne@wardsauto.com