A little bit on Jeep Liberty diesels

Q&A: Diesel lifts Liberty fuel economy by 30%
Oct 12, 2004
Automotive News


There was a time when the diesel experts at Detroit's automakers were some of the loneliest people in the domestic auto industry.

Not anymore.

The Big 3 are working hard and fast to lower diesel emissions so that they can offer the fuel-saving engine in cars and small SUVs.

James Weidenbach, senior manager of the Chrysler group's Diesel Powertrain Product Team, is leading the automaker's effort to put diesels in its vehicles. The first is the 2005 Jeep Liberty available this winter. He spoke last week with Staff Reporter Richard Truett.

Why is the Jeep Libertyusing a diesel engine from VM Motori when Mercedes-Benz makes so many diesels?

The Mercedes diesels have a 2.2-liter (four-cylinder) and a 2.7-liter (engine), which is an inline five-cylinder. Then they go up to their six-cylinder. The Liberty doesn't have room for a five-cylinder. That's a fairly heavy car, a tough, off-road vehicle. With the weight it has, a 2.2-liter is a little bit on the small side. The (VM Motori) 2.8-liter really fits.

How about the Mercedes V-6 diesel used in the E class?

That would be nice. It's a very premium motor. As an engineer, I'm always looking for more cylinders. This started out as a European program. In Europe, our sales and marketing people and consumers wanted to have a four-cylinder engine. That's where the North American version evolved from.

And don't forget that VM is 49 percent owned by us. So it is not truly an outside buy, but it is not Mercedes, either.

Is the 2.8-liter turbocharged four-cylinder diesel engine in the North American Libertythe same engine used in the European version?

It is not the same motor that has been used in the European Cherokee up to this point. The 2005 engine is a new engine. We've gone to a second-generation common-rail (fuel injection system) and a high-pressure variable-rate turbocharger.

The European and U.S. versions have some differences due to fuel differences in the U.S.

What happens in the fall of 2006 when the lower sulfur diesel fuel becomes available? Will you have to recalibrate the engine's software on vehicles you are selling today?

We don't know. Clean fuel will be better. We are meeting emissions with the fuel that is out there. The better fuel helps. The cleaner fuel will allow us in later years to make changes. From a calibration standpoint you want to do a lot of balancing between emission limits and the capability of your engine to produce power and torque.

What is the EPA rating for the diesel Liberty?

We believe the rating will be 22 mpg city and 27 mpg highway, about a 30 percent bump up in what you'd expect from a gasoline version.

Diesel engines don't produce as much smoke as they used to. Why?

Primarily right now it's combustion control. There are some other devices coming down the pike such as the diesel particulate filter, which really scrubs the smoke out of the exhaust. You can still get into some smoke with anyone's diesel, especially with our fuel. But it's much less than what you are used to seeing on traditional diesels.