We first heard of Hennessey’s wild idea to add an extra axle to the already bonkers Ram TRX in 2020. That’s when the tuner teased the Mammoth 1000 TRX 6x6 – a six-wheeled, 1,000-horsepower monster truck monstrosity. This isn’t the company’s first six-wheeled machine, so the announcement wasn’t a surprise. Today, Hennessey has announced that the TRX 6x6 is finally rolling off the production line.

That’s an eye-watering price, though there is likely nothing comparable to it on the road right now. The truck is massive, measuring 88 inches (223.52 centimeters) wide and nearly 7 feet (2.1 meters) tall. However, those numbers pale compared to the length, which is 283 inches (719 cm).

Gallery: Hennessey Mammoth 1000 TRX 6x6

“Everything on the Mammoth 6×6 is bigger, badder, and more imposing – plus, it’s still super-fast, while being a total powerhouse off-road. It’s the undisputed king of the road,” said John Hennessey, the tuner’s owner.

Propelling the massive beast is the same engine from the Ram TRX – a supercharged 6.2-liter V8. However, Hennessey has added numerous upgrades, including a 2.65-liter supercharger, to crank up the output to 1,012 horsepower (754 kilowatts) and 969 pound-feet (1,313 Newton-meters) of torque. The TRX’s stock engine is no slouch, pumping out 702 hp (881 kW) and 650 lb-ft (516 Nm) of torque straight from the factory, but that’s rarely enough to satisfy Hennessey.

The tuner added new supercharger pulleys, upgraded spark plugs, high-flow fuel injectors, a crankcase ventilation system, software calibration upgrades, and more. Hennessey also added the third axle with a lockable differential that required extending the wheelbase and bed. The truck also features new front and rear bumpers, extra LED lighting, and 20-inch 10-spoke Hennessey wheels with 37-inch off-road tires wrapped around them.

There’s a front leveling kit, upgraded electronic fold-out steps, embroidered headrests, Hennessey and Mammoth badging, and a two-year warranty. The truck is the largest that Hennessey has ever built, and with only 12 planned for production, it’ll be a rare vehicle. And it’ll be expensive, with each costing in excess of $449,550.

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