[Icebreaker]

In the following govt web site
http://www.fueleconomy.gov/feg/findacar.htm

they list the diesel
Grand Cherokee as receiving 17mpg City and 22mpg Highway
Mercedes ML320 18mpg City and 24mpg Highway
Mercedes GL320 (bigger and heavier) as 18mpg City and 24mpg Highway

The current Wrangler JK 4wd is listed:
15mpg City 19mpg Highway.

Asuming the Wrangler is about as heavy as the above vehicles...
The incremental jump for a Wrangler would be about a twenty percent fuel mileage increase to change over to a diesel of the the same size. It isn't as dramatic as I would have thought or was hoping for, but maybe the mileage goes up as the diesel breaks in.

It is also noteworthy that checking the fuel mileage of some cars and trucks (Honda Element 2wd for example), the automatics are sometimes giving much better fuel figures. Again, I would have thought otherwise! DC is currently investing in new automatics that might make their way into the JK someday. Someday.

[UTAH]

Originally Posted by Icebreaker

Asuming the Wrangler is about as heavy as the above vehicles...
The incremental jump for a Wrangler would be about a twenty percent fuel mileage increase to change over to a diesel of the the same size. It isn't as dramatic as I would have thought or was hoping for, but maybe the mileage goes up as the diesel breaks in.

Yes - the MPG goes up as both gassers and diesels break in (diesels just tend to break in much slower).

Something to also consider with the cost differential between gassers and diesels: The cost of diesel fuel where I live is usually very close or equal to the cost of premium gas. Of course, my JK takes regular fuel. So... though a CRD JK may get about 20% better MPG, you have to consider that the diesel fuel will be about 10% more expensive than regular. That cuts the economic gain from going to a diesel in half. Thus, one has to consider whether a $3,000 option (per the CRD Grand) is economically worthwhile for 10% in net savings.

Now, don't get me wrong. I like diesels. I have a diesel Cummins Ram that averages 16 MPG. The gasser HD Rams get around 10 MPG. And, my Mercedes E320 diesel once got a low of 25 MPG and regularly averages between 30 and 35 MPG. But, like I said in another thread about diesel JK's - I expected the CRD Liberty and CRD Grand to get better MPG than they do. I think part of the problem is the inefficient auto trans that we're getting with those vehicles. For best MPG, I'd still go with the manual trans.

Bill

[DanW]

Here's an interesting article regarding EPA estimates...
http://www.dieselforum.org/newsartic...7/42/neste/19/

One section in particular-

“As can be seen, diesels appear to perform the best with respect to their label fuel economy, outperforming the label by 4.3%,” the EPA technical support document said. Diesel was the only power source to see an increase in real-world MPG. Gasoline cars decreased by between 1.4%-1.7%, while hybrid owners saw their real-world mileage drop by over 8% compared to the current fuel economy label.

The full EPA report can be found at-
www.epa.gov/fueleconomy/420r06017.pdf

Also, take a look at the 3.0 CRD GC's MPG figures on jeep.co.uk. After the Imperial to US MPG conversion it's- (approximately)
Combined Cycle 23.0 mpg
Extra Urban Cycle 27.3 mpg
Urban Cycle 18.0 mpg

Looks better than the US published numbers for some reason...

[liquids]

Originally Posted by UTAH

Something to also consider with the cost differential between gassers and diesels: The cost of diesel fuel where I live is usually very close or equal to the cost of premium gas. Of course, my JK takes regular fuel. So... though a CRD JK may get about 20% better MPG, you have to consider that the diesel fuel will be about 10% more expensive than regular. That cuts the economic gain from going to a diesel in half. Thus, one has to consider whether a $3,000 option (per the CRD Grand) is economically worthwhile for 10% in net savings.

I did a historical check of diesel vs. regular gas prices over the last 15 years and they are just about at parity over the long haul.
Let's say a gas JK 2-dr gets 20 mpg.
Gas is $3.00 per gallon, or $.15 per mile.
Twenty percent better is $.03 per mile improvement
That's 1% of price of a gallon each mile.

Everyone can do their own figuring on how many miles it'll take to pay off whatever the engine costs at whatever the gas price is, assuming pas-diesel price parity.

[flyrx]

My CRD WK gets about 21.5 mpg. The 2007 sticker claims 20mpg city and 24 mpg highway. I believe most of the guys on the WK forum with gassers do well to get 16-17mpg, with some getting much worse. So on average the diesel WK gets about 25% better mileage than the gas burner.