April 4 isn't a national holiday, unless you're a serious off-roader.

Ram 1500 TRX

2021 Ram 1500 TRX (Ram)

Automakers and truck fans have claimed 4/4 as 4x4 Day to celebrate their favorite vehicles and pastime.

In honor of the date, here's a look at some of most-powerful serious 4x4 off-road pickups and SUVs currently available in the U.S. from the major brands.

Nissan Titan Pro-4X

Nissan Titan

The Nissan Titan Pro-4X features a 400 hp V8. (Nissan)

The Nissan Titan lineup has one thing in common across its models, including the rugged Pro-4X: A 5.6-liter V8 with 400 hp and 413 lb-ft of torque.

Chevrolet Silverado ZR2

The Silverado ZR2 features a unique suspension system that makes it the most extreme version of the full-size pickup and is equipped with Chevy's tried and true 6.2-liter V8, which has 420 horsepower and 460 lb-ft of torque.

Toyota Tundra TRD Pro

The Toyota Tundra is all-new for 2022 and the TRD Pro is king of the model's hill. It trades the V8 of the previous generation Tundra for a 3.5-liter twin-turbocharged V6 hybrid powertrain that combines the internal combustion engine and an electric motor to put out 437 hp and 583 lb-ft of torque.

Ford F-150 Raptor

The F-150 Raptor was the original high-speed off-road factory pickup and the latest third-generation model is the fastest yet. Its 3.5-liter twin-turbocharged EcoBoost V6 is the most powerful in the F-150 lineup with 450 hp and 510 lb-ft of torque. It'll soon be getting some competition from the F-150 Lightning electric pickup, however, which will be available soon with a 563 hp/775 lb-ft powertrain, if not the Raptor's hardcore equipment.

Jeep Wrangler Rubicon 392

It took nearly four decades for Jeep to put a V8 engine in the Wrangler and didn't mess around when if finally did. The Wrangler Rubicon 392 is powered by a 392 cubic-inch (6.4-liter) Hemi V8 rated at a big, round 470 hp and 470 lb-ft of torque.

Ram 1500 TRX

The F-150 Raptor was in a class by itself for a decade until the Ram 1500 TRX showed up with a supercharged Hellcat V8 borrowed from the Dodge Challenger muscle car rated at 702 hp and 650 lb-ft of torque.

Rivian R1T

Pedantic truck fans may argue that electric trucks have all-wheel-drive and not 4x4 drivetrains, but the Rivian R1T's four-motor design makes a strong argument for the latter and puts an exclamation point on it with 835 hp and 908 lb-ft of torque.

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GMC Hummer EV

GMC Hummer EV

The GMC Hummer EV's tri-motor powertrain is rated at 1,000 hp. (GMC)

The Hummer EV may only have three motors, but the heavy-duty pickup is currently the most powerful production pickup on sale today with 1,000 hp, 1,200 lb-ft of torque and the ability to accelerate its 9,063 pounds to 60 mph in three seconds.