Tested: 2023 Jeep Gladiator EcoDiesel Makes Its Case

The 2023 Jeep Gladiator Overland diesel is not as quick as its gas-powered counterpart. You can’t get it with the manual transmission or full-time transfer case. The diesel model also weighs an extra 500 pounds and its maximum tow rating is lower than that of a gas-powered Sport S Max Tow. The Italian-built 3.0-liter diesel V-6 is louder than the 3.6-liter gas engine, both at idle and at 70 mph. It also adds a total of $4650 to the sticker price and requires fuel that, as of this writing, costs an extra $1.38 per gallon, on average. Oh, and there’s diesel exhaust fluid to think about because running out of that could leave you stranded. Now allow us to explain why maybe you should want one anyway.

First of all, you’ll be unique. Most Gladiators are not diesels for reasons that attentive readers may have gleaned from the above paragraph. Moreover, most light-duty trucks no longer offer a diesel—Ford killed its 3.0-liter Powerstroke for the F-150, Ram axed the diesel option from the 1500, and General Motors banished the Chevy Colorado and GMC Canyon’s 2.8-liter Duramax in the 2023 redesign. This leaves the Gladiator and GM’s half-ton trucks, with their wonderful 3.0-liter straight-six, as the lone keepers of the oil-burning flame. For at least one more year anyway.

If you’re a business owner, going with the Gladiator diesel may have tax advantages thanks to its heavy-duty axles, which vault its gross combined weight rating over the 6000-pound threshold where the IRS believes real work trucks dwell. Of course, the same can be said of gas-powered Rubicons, Mojaves, and Sport S Max Tow models, but we’re just pointing out that the diesel’s heavy-duty Dana 44s might confer benefits other than bragging rights. Please consult your CPA—colossal pumpkin assessor—to find out if any of that applies to you. We barely know how to use TurboTax.

But speaking of turbos, the Gladiator’s 3.0-liter V-6 has one, which helps it belt out 442 pound-feet of torque between 1400 and 2800 rpm. Meanwhile, the naturally aspirated 3.6-liter gas V-6 makes only 260 pound-feet at a relatively stratospheric 4400 rpm. Looking at our test results, these engines appear evenly matched, with the gas Gladiator recording slightly quicker times in most contests. But the difference is in how they get there. The diesel Gladiator Overland chugs to 60 mph in 7.3 seconds without evidently trying. The gas Gladiator Overland can hit 60 mph in 7.2 seconds, but doing so will require multiple visits to its 6400-rpm horsepower peak, an exercise that feels decidedly sadistic. The diesel gets through the quarter-mile in 15.6 seconds at 87 mph. Which is also slightly in arrears of the gas model, but without the feeling that you’re trying to ride an extremely angry mule down the backstretch of the Breeders’ Cup.

The diesel is a $4150 option, available on most trims and paired with the 8HP75 heavy-duty transmission that’s more commonly found behind V-8s. The 8HP75 is built by ZF in Germany and was a sneaky bargain prior to 2023, since Jeep added the same $2000 upcharge it applied to the U.S.-built 850RE that’s paired with the 3.6-liter. For 2023, though, the 8HP75 transmission costs $2500, bringing the total diesel spend to $4650. You can’t get the diesel on a base Sport or Mojave, but you can spec it on all the other trims, including the range-topping High Altitude model.

And on the topic of high altitude, that’s where a Gladiator diesel will have another advantage over a gas model, thanks to its forced induction. At sea level, the 3.6-liter has the edge on horsepower (285 horses to the 3.0’s 260), but drive to Crested Butte and it’ll be a different story. Mountain folk—your preppers, off-the-grid hippies, overlanders, fugitives, and hermits—are going to want the diesel, trust us.

Because, for another thing, the diesel offers more range despite its smaller fuel tank. The EPA rates the gas-powered automatic Overland at 19 mpg combined and the diesel at 24 mpg combined (28 mpg on the highway). We found the difference to be even more extreme, recording 14 mpg observed fuel economy in the gas Overland and 23 mpg in the diesel. The diesel Gladiator’s 75-mph highway fuel-economy result was also impressive at 27 mpg, six better than the gasser. Those numbers bolster the subjective expression that the gas engine is working hard in its everyday business while the diesel is relaxed and happy with its role as a truck engine. They also mean that despite the current price disparity between regular unleaded and diesel, the oil-burning Gladiator should gradually recoup its upfront cost. And we mean really gradually, like beyond-100,000-miles gradually, but if the gas vs. diesel price relationship returns to where it was a year ago, the Gladiator’s diesel powertrain would pay for itself in less than 60,000 miles (not counting the occasional swig of DEF). Or even fewer miles if you’re frequently towing. Plus, you can put your spark-plug budget toward the lift kit and bigger tires that the Overland needs to visually offset its wiener-dog proportions.

Now, we did mention that the Gladiator diesel is noisier at idle and cruising speed, but at wide-open throttle, it’s much quieter—72 decibels to 77—which again points to its comportment. And the sounds it makes are cool, if you appreciate the determined clatter of compression ignition and the scree of a turbocharger working in concert with a fuel-injection system pressurized to 29,000 psi. It’s the aural signature of a truck that you hear before you see it, materializing out of a blizzard carrying tow straps and spare fuel cans like a Saint Bernard with a keg around its neck.

If you hate that sound, then maybe the Gladiator diesel is not for you. This is, after all, a convertible body-on-frame pickup truck with solid axles and removable doors. In upscale Overland trim, it’s a caveman in business casual. It’s a freak, a collector’s item, the kind of pet project you’d expect Jeep to roll out at the Easter Jeep Safari and then forget about. The diesel might not be the engine most people get, but it’s the one a Gladiator ought to have.