2025 GMC Sierra 2500 Denali Ultimate Duramax Review

If you like big trucks, or you tow a heavy load, I have one for you this week you’ll love:  The 2025 GMC Sierra 2500 Denali Ultimate, one of the biggest, baddest trucks GMC offers.  It is an amazing combination of capability and luxury.

Exterior  

As you walk around the refined exterior in Sterling Metallic, you see the big GMC mesh grill, front tow hooks, LED headlights and taillights, fog lamps, 20” wheels, and a functional hood scoop.

I love the deployable running boards that stay out of your way but are actually usable when they drop down. There are side steps at the front of the bed, corner steps in the rear bumper, and then of course, the Multi-Pro tailgate that is power and turns into a step to get into the bed. 

Under it is a Kicker stereo with speakers for your tailgating pleasure.  You just can’t help but notice the enormity of this truck that weighs almost 3 ½ tons, and its huge trailer towing mirrors.  It is a beautiful truck. FYI, the big mirrors will power-fold in to allow you to visit your favorite drive-through car wash.

Powertrain

Under the big, bulging hood is a 6.6-liter Duramax turbo diesel engine that is putting out 470-horses, but most importantly 970-pound feet of torque.  It is mated to the great Allison 10-speed automatic transmission, and this truck is 4-wheel drive.  The feeling of almost 1000-pound feet of torque is just incredible, and I feel quite sure that you could put an 18,000 pound or more trailer behind this beast and it would take off exactly the same.

Interior 

As you enter the spacious cabin, the interior is luxurious.  The seats are comfortable, large, full-grain leather, they are heated and cooled, and they will massage you.  Both front seats are 16-way power-adjustable. Beautiful stitching is everywhere, and all materials are soft to the touch.  Open-pore Paldro wood adorns the dash, and it is just beautiful.      

From the driver’s seat, you see a large 12.3” gauge cluster that is colorful and easy to read.  There is a configurable driver info center that you scroll through from the steering wheel that will give you a plethora of information including your range, engine temperature, your battery amperage, oil pressure, a tachometer, and which 4-wheel drive mode you are currently using.

The Denali Ultimate has a huge 13.4-inch infotainment touchscreen that sits on the dash.  It operates the 12-speaker Bose sound system, Bluetooth, navigation, Wi-Fi, wireless Apple CarPlay and Android Auto, and Google Assistant. The screen moves lightning fast and everything is easy to understand.

A swipe to the left gives you the trailer towing settings, climate, vehicle settings, and more.  You can configure the buttons as you wish and add and delete them as you choose.

Under that are A/C controls, and a row of buttons that will do many things, most notable is to turn on the lane assist, activate the parking assist, activate the exhaust brake, lower the tailgate, and you can lower all 4 windows at one time. Next to it is a large, square button to start the big truck if you don’t use your key fob.

The gear shifter on the 2500 is old school and sits on the steering column. The center console houses two large cupholders, two USB-C ports, a switch for trailer brakes if you are towing, and a wireless cell phone charger.  A supple center storage area is large and makes for a very nice place to rest your elbows.

Moving to the second row of seating, there is tremendous leg and headroom, the split seat is heated, there are air conditioner vents, a fold-down armrest with cup holders, and USB and USB-C ports.  The seats fold up from the bottom for additional storage and there is storage built into the back of the rear seats.  If you fold the bottom of the seat up and out of the way, there is a massive amount of room to keep cargo safe inside, or if you have a dog, he or she can lay out and be very comfortable no matter the size.

Standard Features 

This Sierra Denali has all the popular comfort and safety features you want including: a tilting, telescoping, and heated steering wheel, lane departure warning, automatic emergency braking, forward collision alert, blind spot warning, deployable running boards, remote start, rear seat reminder, a power moon roof, rear camera mirror, a head-up display, safety alert seat, HD surround view camera, and trailer-included blind spot monitoring.

Options 

Options total $2,035 and include the $1,535 Max Trailering Towing package, and the paint runs $495.  Everything else we discussed comes as standard equipment.

Ride and Drive  

Make no mistake, this is a huge truck with a ton of power that is capable of towing 20,000 pounds. The truck rides great, the cabin is super quiet, and there is very little discernible noise coming from the big diesel engine. Like all heavy-duty trucks, it can be challenging to park in spaces that were built for cars. 

What You'll Pay

feel sorry for people trying to choose a heavy-duty diesel these days.  The Ford Powerstroke is terrific, the Ram Cummins is great, too.  Then you have to have the Chevy and this GMC on your consideration list, as well.  Luckily, they all have attributes that are unique and before deciding, you really should look at them all.

I can assure you that if you go with the professional grade GMC, you won’t be disappointed.