What do the rating stars mean?
With EPA ratings of 20 mpg city/24 mpg highway, pop the 5-speed automatic transmission into gear and get ready for off-roading, inclement weather or the fast-moving freeway. With a base price of $37,645, this mid-size SUV carries a 3-year/36,000 miles limited warranty and a lifetime/unlimited mileage powertrain warranty. Our tester rang in at $42,520, with $3,700 allocated to the powerful 3.0-liter V6 turbo diesel engine bearing a Mercedes imprint. Fill ‘er up with B5, let’s hit the road.
Initial Impression: This is gonna be fun
Scott: "It’s no secret that I’m a big fan of diesels. Their seemingly endless low end power is legendary (that’s why they use ‘em in big trucks and heavy duty equipment.) They just have that sound, that clickity-clack, that’s so comforting—yeah, even the modern engines still have it, if faintly. And of course, cubic inch for cubic inch, they are the kings of fuel efficiency. Knowing all this, it’s easy to understand that I was hankerin’ to drive this guy."
Christine: "I’ve always liked the 4x4 Jeeps—complete with the roll-bar and beefy off-roading clearance and tires—with the top down and tunes blaring, of course. Having never driven a Cherokee, I was looking forward to checking out the styling and handling of this biodiesel-burning everyday civilized SUV."
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Look & feel: One smooth shave
Even if you live in the mountains of northern California where summer brings dry gravely roads and winter brings rain and wash-outs, it’s the rare person who buys a Jeep Cherokee and needs it to go 4-wheeling the majority of the time. And unless you’re driving a beater and lovin’ it, you’re probably wanting some comfort and convenience thrown in, and that’s where this Jeep shines. Slide into the leather-trimmed two-toned bucket seat, grab hold of that leather-wrapped steering wheel and you’re off.
Oh, and did we mention that you ought to fill up with biodiesel first, too? That’s right—Jeep recommends the use of B5 in this Grand Cherokee, or ULSD (Ultra Low Sulfur Diesel)—whatever is the cleanest fuel option available in your neck of the woods. Look around the interior and you’ll feel like you’re in a Jeep—sure, it’s got all the bells and whistles, but it’s not overly pretty. Just enough square edges and rough and tumble feel to appeal. Comfy adjustable driver’s seat—check, roomy pleasing back seats—check, 60/40 fold-down second-row bench seats—check, cupholders galore—check, 35 cubic feet of rear storage—check.
Now turn the key and hear the quiet diesel click. Now that’s where we’ve got more to say—read on.
Fuel-ability: Clean and just a little mean
The good folks at Chrysler made the right choice when they decided to wedge this potent little oil burner between the fender wells of the Grand Cherokee. That’s right, we said oil burner. Diesel fuel (as well as biodiesel) is considered an oil, albeit a very light and thin one.
Our Grand Cherokee was powered by a Mercedes-built 3.0-liter V-6 turbo diesel that cranked out power across a broad, flat torque curve. All 376 ft. lbs. of torque are fully unleashed at a mere 2000 RPMs and wow, could we ever feel it. This Jeep pulled like it had a V-8 under the hood. That big chunk of instant torque is courtesy of a single variable geometry turbocharger that the Chrysler folks call a Variable Geometry Turbine (VGT). It’s basically an exhaust gas driven turbo that has electrically adjustable blades that are set to produce a high velocity, charge boost of air at initial vehicle acceleration—and then swing to a position that produces high volumes of air charge at high engine speed.
Compared to the previous generation 2.8-liter diesel I-4 (the one that powered the diesel Jeep Liberty), this 3.0-liter V-6 is light years advanced. This is in no small part due to the clean emissions requirements for U.S. bound diesels. The list of refinements is long and impressive, from third generation common rail injection to electrically controlled air intake throttling.
The Enviro-meter: Diesel power, gasoline emissions
All 2007 diesels must meet stringent clean diesel emissions to be sold in the U.S. and the diesel Cherokee is no different. How’s it done? Mostly through very efficient and precise fuel delivery, rigorous exhaust scrubbing, and of course, clean fuel.
The fuel delivery is handled by a high pressure (24,000 PSI) common fuel rail and individual piezo-electric injectors. This combination allows for variable injection cycles that render absolute spot-on fuel metering. Exhaust gas cleaning is via an oxidation catalyst and a diesel particulate filter in the exhaust stack. These two components reduce levels of hydrocarbons and CO by about 50 percent and soot by about 90 percent. Finally, the fuel itself must be super clean Ultra Low Sulfur Diesel (ULSD) or a ULSD/biodiesel blend. Chrysler currently allows only a 5 percent biodiesel blend, but look for that restriction to be relaxed as emissions technology advances. All combined, these three pieces of the clean diesel puzzle cut what was once sooty black, oily and sulfur infused exhaust gas to emissions of approximately gasoline engine levels.
Our only knock against the Grand Cherokee diesel was our observed fuel mileage. Diesels are by nature extremely efficient, but we had a hard time getting our fuel economy to break 20 MPG. That’s not bad for an SUV, but we think a lot of economy was left on the table by the inefficiency of the Cherokee's Quadra-Drive II system. Overcoming the extra friction and weight of the full-time AWD drivetrain created extra work for the engine, work that translated into extra fuel consumed.