The Jeep Wrangler, arguably the best off-road SUV on the planet, just got better. For 2020, there's a new, diesel engine under the hood -- something Wrangler fans have been wanting for years. It's nearly the same 3.0-liter EcoDiesel engine you'll find in the new Ram 1500, and makes the Wrangler easier to live with, both on- and off-road.It doesn't take long to fall in love. With 260 horsepower and -- more importantly -- 442 pound-feet of torque (the Ram puts out 480 pound-feet), the Wrangler smoothly eases into traffic, and passing slower trucks on the highway is hardly a problem. The Wrangler's eight-speed automatic transmission has been reprogrammed to properly handle all of that torque, and it downshifts quickly, meaning there's no lag before power delivery when you're driving in traffic.Now, don't think this diesel engine suddenly turns the Wrangler into a hot rod. Yes, the acceleration is effortless, but the diesel-powered Wrangler drives largely like the gasoline I4 and V6 models. You'll notice a bit of diesel rattle making its way into the cabin, but the wind noise the Wrangler generates at 70 to 75 mph is enough to cover up any powertrain rumbles.Where the diesel engine really improves the Wrangler's prowess is off the beaten path. Utah's Sand Hollow Reservoir OHV park has a great mix of soft sand and rocky trails, and it's the perfect place to see how that 442 lb-ft of twist handles hard-core off-roading. This course is full of slick rocks with ledges and shelves that would make a stock Toyota Tacoma shudder in fear. On the Wrangler, the 33-inch BF Goodrich KO2 tires have been aired down to about 25 psi to make a bigger contact patch. The Wrangler completes the course in 4WD High pretty easily, the diesel-powered rig climbing up the steep rock faces in first gear like they're nothing. The only time I ever need to use 4WD Low is when I encounter some really soft sand. This Rubicon tester has all the same off-road goodies as gas-powered Wranglers, with approach, departure and breakover angles of 44, 34 and 22 degrees, respectively. Skid plates and rock rails protect the underbody (and the diesel exhaust fluid tank), while Dana 44 axles do the heavy lifting.With the diesel engine, the Wrangler Rubicon's axle ratio is 3.73:1, compared with 4.10:1 with the gasoline engines. Jeep says this less aggressive ratio helps with fuel economy; a numerically lower axle ratio allows for better efficiency at the expense of power. In the end, the diesel Wrangler's crawl ratio is 70:1, compared with 77:1. But remember, that ratio is simply a representation of how much the torque is multiplied through the axles before it hits the ground. So even though it has a weaker crawl ratio, because the diesel engine has 442 lb-ft of torque compared with the 260 or 295 available with the gas powerplants, you still come out ahead.We don't yet have official EPA fuel economy ratings, but Jeep estimates a 500-mile driving range with a full tank of diesel. With a 18.5-gallon fuel tank, that math equates to roughly 27 miles per gallon, but again, that's just an educated guess. For what it's worth, the most fuel-efficient 2.0-liter Wrangler returns 22 mpg city, 24 mpg highway and 23 mpg combined.As with other Wranglers, the diesel version is available with a decent amount of driver-assistance tech. The blind-spot monitoring can be customized to deliver a visual or audible warning, or both. You also get adaptive cruise control and forward-collision warning.A 5-inch infotainment screen is standard, but this Rubicon tester packs the larger, 8.4-inch Uconnect screen. I love Uconnect -- it's easy to use, and has Apple CarPlay and Android Auto bundled as standard. The embedded navigation is simple to use, and I like that it will tell you your exact latitude and longitude coordinates, which makes it perfect for real back-country exploration. There are four USB ports, two 12-volt outlets and a 115-volt, three-prong outlet scattered throughout the Rubicon's interior, though lesser models have slightly fewer charging ports.When the diesel-powered Wrangler hits dealers in December, it'll only be available on four-door Unlimited models, and you can't have it with the SUV's six-speed manual transmission. It's also kind of expensive: A base Sport trim starts at $39,290, including $1,495 for destination, while a fully loaded Rubicon like the one you see here tops out at $63,145. Yowza.Still, I can't think of any truck or SUV that can match the Wrangler's off-road prowess, and the diesel engine just makes it more engaging both on- and off-road. I'm excited to really put this oil burner through its paces on a longer off-road course in the future. And I'm doubly stoked about the upcoming Gladiator EcoDiesel, too.Editors' note: Travel costs related to this story were covered by the manufacturer, which is common in the auto industry. The judgments and opinions of Roadshow's staff are our own and we do not accept paid editorial content.