2020 Jeep Wrangler EcoDiesel First Drive Review

How about some diesel torque for your rock-climbing adventures?

ZION NATIONAL PARK, Utah—According to Jeep, the 2020 Wrangler JL diesel will satisfy the number-two demand it hears from its enthusiasts. (The top demand, a pickup, has been filled by the Gladiator, while the number-three request is for a new Grand Wagoneer. That's coming.) Never mind that there isn't much U.S.-market historical precedent for such a Jeep engine—Willys offered a 3.2-liter British Perkins diesel four in the CJ5 and CJ6 from 1961-65, while a 2.2-liter diesel can be had in European-market Wranglers—truck fanatics, and by extension off-roaders, love them.

And why not? The low-end torque, even accounting for inevitable turbo lag, makes rock climbing easier. It also was one of two solutions developed to help Jeep meet the now-suspended 54.5-mpg 2025 Corporate Average Fuel Economy standard in the U.S., which loomed as this engine was under development. Now that it's here, it will be available only in the four-door Unlimited's Sport, Sahara, and Rubicon trims, and mates only to an eight-speed automatic transmission.

The EPA has not published the EcoDiesel Wrangler's official fuel-economy numbers just yet, although they should come soon, as the first deliveries are expected by early December. Still, Jeep's North American head Jim Morrison says to expect well over 500 miles of range with the Wrangler Unlimited's 18.3-gallon tank, as well as a 7-to-8-mpg gain over the 3.6-liter gas V-6's 22-mpg EPA highway mileage. If the Jeep Wrangler Unlimited EcoDiesel's EPA highway number doesn't hit 30 mpg, it certainly will hit 29. The EcoDiesel is a $3,250 option over the 3.6-liter gas V-6, with pricing starting at $39,290 on the Sport.

2020 Wrangler Diesel: EcoDiesel Version III

Unlike the Ram 1500 that also offers an EcoDiesel V-6, the Wrangler is built for tough terrain and fording water, so the 3.0L turbodiesel in the Jeep is a "complete redesign," which began by raising the oil sump's location from the bottom of the engine, says Mauro Puglia, Fiat Chrysler's North American senior manager for diesel engines. The realigned oil sump knocked over a row of dominos, forcing Puglia's team to make a number of other changes that results in EcoDiesel III. The '17 Jeep Grand Cherokee got EcoDiesel I, while II is what's in the latest Ram 1500.

EcoDiesel III has redesigned lightweight aluminum pistons with thinner rings and low-friction diamond-like carbon coating on the pin and compression ring to reduce parasitic losses. The piston pin is offset by 0.3mm from centerline for better noise, vibration, and harshness (NVH). In addition, the engine also has a new-generation water-cooled turbo, redesigned cylinder-head intake ports, updated exhaust-gas recirculation, high-pressure 29,000-psi direct-injection fuel-injector nozzles, and a 16.0:1 compression ratio (down from 16.5:1) for better fuel economy and reduced engine noise. The Rubicon EcoDiesel comes with the Rock-Trac two-speed transfer case with a 4.0:1 low-range gear ratio, while the Sport and Sahara trims come with the Command-Trac part-time two-speed transfer case with a 2.72:1 low-range gear ratio. As mentioned, all transmit power through the TorqFlite 8HP75 eight-speed automatic.

The diesel itself contributes approximately 375 pounds to the Wrangler EcoDiesel's 400-to-425-pound weight gain, Puglia says. There's also more sound attenuation, and a 5.1-liter diesel exhaust fluid tank just behind the fuel tank. It's refilled via a port under the same driver's side flap as the fuel filler, and a message on the dash indicates when it's time to refresh the tank, generally in 10,000-mile intervals.

The most important number for Jeep enthusiasts is this, however: 442 lb-ft of torque at 1,400 rpm. Horsepower, if you're interested, is 260 at 3,600 rpm and the engine tops out at a 4,600-rpm redline. (The 1961-65 Jeep CJ5 and CJ6's optional Perkins engine was rated for 62 horses and 143 lb-ft according to our sister publication Diesel Power.) This all adds up to a quiet, fun-to-drive modern diesel. It's quiet when the windows are rolled up, the top is closed and you're inside. Roll the windows down or crack the optional power canvas top open, especially in a tunnel, and it's like you've driven into a truck stop full of idling semis. Every modern diesel makes a similar amount of noise, though.

2020 Wrangler Diesel: Driving On- and Off-Road

The windows were up and the power canvas top closed most of the time until after our drive through beautiful Zion Canyon, whose red and tan Navajo sandstone contrasted beautifully with our Ocean Blue Metallic Unlimited Sahara. This national park is one big speed zone with a solid double stripe splitting the two-lane, so the on-road drive on the twisty ribbon of blacktop was at the moderate speeds befitting a Wrangler wearing BF Goodrich K02 all-terrain tires.

The V of NVH fame were present, but only just and with none of the H. Diesel engine vibration is a constant and steady low-grain feel that comes through the steering wheel and floorboard. It's of the level you'll find in virtually any new diesel, including the engines that come in more refined luxury SUVs.

On pavement and in rear-wheel-drive 2Hi mode, the EcoDiesel's tip-in feels soft. It's typical of a diesel engine's turbo lag and not an issue in this traffic, though in heavier urban traffic I'd be more reluctant to roll the Jeep into a close gap. A diesel's lag is more pronounced than a gas engine's—a difference we grew intimately accustomed to with our recent long-term Land Rover Discovery 3.0-liter diesel. Once underway and with the turbo spooled up, though, the power is healthy in the mid-range, offering progressive acceleration befitting the smooth feel you'd want from a tall off-roader on knobby tires.

Perhaps even more so than with any of the gasoline engines, the EcoDiesel Wrangler's on-road compromises ride off into the sunset once you get this beast moving up and down tall, narrow rocks. In this part of Utah, that would be at Sand Hollow State Park, where Jeep outfitted us with a Sting-Gray Rubicon, its tires deflated to 20 psi from the recommended 37.

Once through the sand and up to the rocks, we switched from 4Hi to 4Lo, made sure the lockers were locked, and detached the electronically actuated anti-roll bars. We were fourth in a row of four Unlimited Rubicon EcoDiesels, with spotters regularly waving us to positions pointed toward the clouds with no view of anything but sky.

Here, the EcoDiesel shines. With the turbo boost several hundred rpm away from the 800 to 1,200 we were conjuring, it took just the slightest tip of the throttle pedal to smoothly inch the Wrangler across the rugged terrain. Sometimes it took a deliberate blip to step up a tall obstacle; we covered the brakes as the Jeep leveled on the rocks, the underbody making the sort of scraping noises that usually make us cringe. Those are the skidplates doing their job. That low-hum diesel vibration feels tactile here, too, and almost reassuring in this setting.

The four-Jeep convoy eased down the final rock of our journey and headed out to deep sand dunes, the driveline in 4Hi with the rear differential unlocked. It was sunny and warm, the driver's window down and the power folding top half open, and the idling Jeeps again brought to mind a truck stop. We drove through the sand at maybe 30 mph, the chassis getting a bit loose and requiring a bit of opposite steering lock to stay on course.

Jeep will sell plenty Wrangler Unlimiteds with the EcoDiesel option, and plenty more Gladiator EcoDiesels when that model makes its debut next year. This should push the four-door versus two-door Wrangler mix up past its current high of 90 percent/10 percent (versus about 75/25 for the old JK model). But Jeep has another fuel-mileage trick up its sleeve, a plug-in hybrid under development. That powerplant, potentially with max torque at 0 rpm, will probably go to the European market first, where stringent new CO2 emissions standards take effect in January. We'll leave it to the Jeep aficionados to decide whether they'd prefer to climb rocks with gobs of low-end torque to a soundtrack featuring a diesel's hum or no noises at all.

2020 Jeep Wrangler Unlimited EcoDiesel Specifications
ON SALE Now
PRICE $38,645
ENGINE 3.0L turbocharged DOHC 24-valve V-6 diesel; 260 hp @ 1,400 rpm, 442 lb-ft @ 3,600 rpm
TRANSMISSION 8-speed automatic
LAYOUT 4-door, 5-passenger, front-engine, AWD SUV
EPA MILEAGE 22/30 mpg (est)
L x W x H 188.4 x 73.8 x 73.6 in
WHEELBASE 118.4 in
WEIGHT 4,825-4,875 lb
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