ELKHART LAKE, WI – Launch of a diesel-powered Grand Cherokee in the next couple of months will give Jeep four models rated at 30 mpg (7.8 L/100 km) highway.

The Wrangler will be the sole remaining Jeep not to achieve that fuel-economy rating, with the Compass, Patriot and new midsize Cherokee that replaces the Liberty this fall all delivering 30 mpg.

That could change in the ’15 model year, when the Wrangler is scheduled for a refresh that executives say could include application of the same 3.0L 6-cyl. diesel.

“So far it will be the only one,” Jim Morrison, head of Jeep North American operations, says of the diesel application in the Grand Cherokee during an interview here at the annual Midwest Automotive Media Assn. spring new-car rally.

“Yet, after we announced we were going to have a diesel Grand Cherokee, we got so many positive reactions from consumers and so many customer requests for diesels that we are looking at how to expand the diesel line into other vehicles.”

Morrison won’t say which other Jeeps might get a diesel or when, but he notes Wrangler attracts younger buyers “who understand and accept diesels,” and the addition of the engine presumably would complete the brand’s lineup of 30-mpg vehicles.

The Jeep executive is more eager to talk about the upcoming new Cherokee, considered a vital component in marque’s long-term success and what Chrysler CEO Sergio Marchionne has termed the brand’s “now or never” shot to succeed in the midsize utility-vehicle segment.

“It is,” Morrison says of the now-or-never forecast. “We are absolutely counting on it to be really good.

“It's a big segment (1.6 million to 1.7 million annual sales), so there is a lot of pressure on us, though now that we've experienced three years of growth and profitability, it's pressure, not panic, to do well,” he adds. “Cherokee is the name that originally defined what an SUV was when we first started using it. A lot is on the line – pride in SUV sales leadership.”

While the Cherokee will replace the Liberty in a matter of months, the Compass and Patriot now are expected to continue in the Jeep lineup through 2015, according to a WardsAuto/Automotive Compass production forecast.

After that there are no guarantees, only speculation that only one will survive or perhaps one of the two will be sold in the U.S. while the other will be offered in Europe.

“What will we do with those two? What I know is that I can't tell you,” Morrison says.