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2008 Diesel Jeep Grand Cherokee Road Test

Posted in Project Vehicles on September 1, 2009
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Well, it was a good year with our long-term Grand Cherokee with the 3.0L diesel engine.

Considering our proclivity for soft-top Jeeps, we were surprised at how sad we were to see it go. Not quite selling-a-flatfender sad, but sad nonetheless.

In the year we had it, we managed to rack up 42,105 miles on it towing, road-tripping, and just cruising the US. We made a coast-to-coast-to-coast run, we drove along the Pacific Ocean from Mexico to Canada, we did a day-trip to Portland, Oregon, from Los Angeles, California, and we made it to Moab three times in a year.

Don't think for a second that the Jeep was babied, either. We ran trails with it, towed with it, and drove it through snow that required lockers with our 35-inch tire shod TJ. If we had to guess, we'd say somewhere in the neighborhood of 30,000 of those miles was dragging another Jeep along on a dual-axle car trailer behind the Grand. All the while we were laughing at how the Grand got better mileage towing a Jeep than the Jeep on the trailer would get on its own

After over 100 fill-ups over the course of a year, this was the last one. When we drove the Jeep, more often than not, it would get fuel at least once a day (hey, we did have to write an occasional story). When you consider the 350+ mile range, you can see just how much it did get driven. Hey Chrysler (Fiat?!?!), if you really want a vehicle driven in the real world again in a compressed amount of time, you know where to send it!

When people found out it was a diesel, they'd ask us, "What kind of mileage did you get?" Well, long story short, if we would stay out of the skinny pedal, we'd get 22-23 mpg on the highway, 16-17 mpg in LA city traffic, and 16-17 mpg towing. At the time we thought nothing of it, its just the way it was. Now that the Grand is gone, we are pulling about 8 mpg less on the highway, and the more frequent fill-ups are a killer on long trips. With the Grand, we'd clear 350 miles towing or 450 miles unloaded on a 20-gallon tank. With a regular Jeep, we are lucky to see half that on the same number of gallons. Heck, even Mileage Master only hits 350-400 on a tank, and that's about 23-24 gallons.

Mileage aside, running 1,000 miles in a day for many days consecutively became a no-brainer, towing or not. Want to go to Portland? Denver? Albuquerque? No problem and no airplane needed, either. All of the events Trasborg covered since the Grand arrived were driven to, even the east coast ones.

If we liked it so much, why did we give it back? Well, we did everything we could to hang on to it. Having made it over 40,000 miles with no major issues, we got really curious to push 100,000 and see just how well put together this hoity-toity Jeep with the high-falutin' Mercedes-sourced diesel engine was. Would we kill the transmission with all the towing we were doing? Just how long does a set of brake pads last (we still had plenty of meat on ours at 40K+)? Will all the electrical doodads cause insurmountable issues down the road? Will the blend doors die a horrible death like most other Grand Cherokees? We might never know.

We really expected after all this abuse that we'd have tons of squeaks, rattles, creaks, and groans. There is only so much a unibody Jeep will put up with before flexing. But the day we gave it back it was as quiet and comfortable as the day we got it.

PhotosView Slideshow
We figured by this mileage the stock tires would be toast. However, the Goodyear Forteras that came on the Jeep still had some life left in them, even after all they had been through. Granted, we'd have been looking to replace them after another 5,000 miles or so, but still not bad wear, with no cupping or other untoward issues out of this rubber.

The other question we get all the time is if we'd suggest this Jeep to others. We would, but with a few qualifications. This is a great Jeep to use as a daily driver and weekend tow rig, but if you are looking to tow another Jeep all the time, you should get a heavier vehicle. We towed all over with this thing, but it was a constant battle between balancing the trailer and paying attention to overall trailer weights. With a rated tow capacity of 7,600lbs and 376 ft-lbs of torque on tap, we weren't concerned about the Jeep up and going. However, the wheelbase doesn't lend itself to heavy towed loads, and our trailer was a 1,500lb trailer, allowing up to 6,000lbs of Jeep. Many car-hauling trailers are in the 2,000-2,500lb range, and that means you'd be towing at max capacity with a Jeep decked out for a weekend on the trails. When towing heavier loads, nearer to the max rated capacity, the Jeep did it with no questions asked. However, it would have felt better and been more stable with either a weight-distributing hitch or add-on air bags. The rear coils just don't handle tongue weight as well as a heavier leaf-sprung tow rig.

This is not a simple engine. Every oil change we'd pull the stupid plastic cover and just look at the top of the engine, attempting to ID components and only partially succeeding. It didn't matter, because in all the miles under the wheels, we only had one problem, and that was likely from our cross-country-north-to-south-border marathon. We swapped oil filters at 24,000 miles as advised, but at 39,000 (roughly) miles we were climbing a grade with the Jeepster in tow in 90-degree weather going from 2500 to 7500 ft of elevation and the Grand smelled hot. We pulled over and it died showing an ETC (electronic throttle control) error. We pulled fuses, checked this and that, and about 20 minutes after dying, we were able to restart it and make the rest of our journey. The root cause was a clogged air filter. The tech that worked on it said that it wouldn't have been too much longer until the filter was pulled into the turbo. For our part, we were happy that $20 solved the problem.

Overall, it is a great vehicle. Would we beat on it in the rocks? No, at least not the one we used for daily driver duties. Have we beat on a similar diesel Grand in the rocks? Yep, and the Quadra-Drive does great. If we didn't care about the $43,000 price, we'd build one of these and tow it to the trail with a stock one.

What 42,105 Miles Costs
In the last installment, I broke down the first 24,664 miles to figure out what this diesel Jeep was costing me to run. In keeping with the theme of this long-term test, here are the final numbers on our WK.

* Cost of 2,286.869 gallons of diesel fuel $7,544.88
* 6 cases of 5W-40 Amsoil European Car Formula Oil 669.60
* 6 Mann engine oil filters 76.14
* Napa Air Filter 15.69
* Mopar Air Filter 20.01
* 7 quarts of Amsoil Hydraulic Tractor Fluid (transmission and T-case) 56.00
* 5 quarts of Amsoil 75W-140 Severe Gear Extreme Pressure Lubricant 75.75
* Mopar transmission filter (PN 52108325AA) 23.10
Total parts, fuel, and fluids (all expenses) $8,481.17
($.20/mile over 42,105 miles)

Real World Mileage
The sad thing is that we've now got seven Jeeps that won't see the kind of mileage they saw on a trailer behind the Grand Cherokee. The nice thing is that we saved a ton of money in gas by using a new Grand Cherokee as a tow rig for a whole year. Looking back on the year, here are some of the highs and lows of our fuel consumption.

* Average fuel economy for the year (mpg) 18.41
• Worst Single Tank Fuel Economy (towing an {{{M}}}-37 up a bunch
of steep grades, mpg)
• Best Fuel Economy (in convoy at 65 mph running Interstate 5
south from Portland, Oregon, mpg)
* Highest Single Tank Range (miles) 494
(21.66 gallons to full, 22.8 mpg)

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