We give you 30 days and/or 500 miles to make sure you are happy with your car. If not, simply exchange it.
McMillen Auto Group - Sales
Exterior and Interior
Wearing a Diamond Black Crystal Pearl coat, this 2021 RAM 1500 TRX Hennessey Mammoth 900 is a menacing beast. The Hennessey and Mammoth 900 exterior badging leave no one in doubt about this truck’s title, while the Mammoth custom front and rear bumpers ensure that it doesn’t look like a garden-variety RAM 1500 TRX. Meanwhile, you’ve also got 20-inch Hennessey 10-spoke wheels wearing 37-inch off-road tires to remind you that this truck is happy off the beaten path, too. Entering the cabin is made easier, too, thanks to a front leveling kit and upgraded electronic fold-out steps. Before we climb aboard, let’s take note of the upgraded LED lights in the front bumper, which can turn the darkest trail into a sea of light. The five-seat interior of this 2021 RAM 1500 TRX Hennessey Mammoth 900 is quite practical – in fact, you could use this truck as a family hauler, child seats, and all. It’s got plenty of creature comforts, including a 19-speaker Harman/Kardon sound system, Apple CarPlay, Android Auto, dual-zone climate control, and rear air vents.
Engine
The powerful 6.2L V8 under the hood of this 2021 RAM 1500 TRX Hennessey Mammoth 900 is supercharged, to deliver 912 hp and 873lb-ft. That’s not all, it drives all four wheels via an 8-speed automatic transmission, and has a Mammoth stage 2 off-road kit. Further highlights include a ported supercharger snout, an upgraded overdrive crank bumper, a high-flow filtration system, and high-flow fuel injectors. Then, we’ve got a Hennessey ECM and TC calibration upgrade to manage the upgraded power.
We give you 30 days and/or 500 miles to make sure you are happy with your car. If not, simply exchange it.
If you find a lower price on another website, within 30 days, we’ll refund you the price difference.
Backed by thousands of reviews, our customers love shopping for used cars at Auto Boutique.
Our Free Exchange Policy adds even more transparency and comfort when buying your next vehicle.
This vehicle has many great features, but we understand that you still may have questions. Please use the form below to request additional information and we will respond with all the answers you need.
©2025 McMillen – All rights reserved.