Wed. Jul 28th, 2021

Powerful Diesel Performance

The 2021 GMC Sierra 1500 Duramax 4WD Crew Cab
AT4 CarbonPro showed-up in my driveway and the neighbors took notice. Only of a
few of them would be considered “truck people”, so their comments were
interesting. I heard how nice it looked, how it wasn’t overly garish and, while
big, it wasn’t too big. This last one
was curious as this truck is pretty darn big! But maybe since the predominant
vehicles on the road these days are midsize to large SUVs, a big truck really
isn’t so big.

Power and Torque and Fuel

2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro
Brains and brawn

Clean Fleet Report
recently drove the 2021 GMC Sierra 1500 4WD Crew Cab AT4, powered by a
3.0-liter Duramax turbodiesel engine. The numbers of 277 horsepower and 460
pound-feet (lb.-ft.) of torque, while mated to a 10-speed automatic
transmission, only begin to tell the story of smooth performance with plenty of
grunt when needed. There is a low diesel rumble upon start-up that becomes a
nice note when accessing the ample torque to get off the line, but then purrs
at freeway speeds. Stand next to the hood when the engine is at idle, and you
will be amazed at how quiet it is. About that torque: you get full max 460 lb.-ft.
at a very low 1,500 rpm. This means that when you are towing up a grade, it
will pull strong and still deliver good fuel economy. Not enough can be said
about how excellent the General Motors 3.0L Duramax turbodiesel is.

2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro
The heart of the truck

Weighing in at 5,640 pounds,
the Sierra 1500 AT4 has a maximum payload of 1,810 pounds and can tow 8,800
pounds. These numbers are a bit lower than competitor trucks, but the trade-off
is better fuel economy in exchange for less payload and towing.

Fuel economy for the 3.0-liter
Duramax turbodiesel is EPA rated at 22 mpg city/26 highway/24 combined. In 235
miles we averaged 25.2 mpg, but on a 100-mile all-freeway run with the adaptive
cruise control set at 65 mph, we got an impressive 29.8 mpg. When fully loaded
or pulling a trailer, mileage numbers will be less. But nudging 30 mpg is
impressive, which was aided by the engine stop/start system, which shuts off
the engine rather than idling. Fuel economy numbers reported by Clean Fleet
are non-scientific and represent the reviewer’s driving experience
using the dash gauge computer. Your numbers may differ.

On the Road: Smooth and Responsive

The Sierra 1500 AT4 was
comfortable out on the road, where it shines on long distance trips. The even
acceleration, with very useable torque coming on at 1,500 rpm, made it a breeze
to drive in-town or on the freeway. Even under the most severe road conditions,
the Sierra’s ride was never rough with little road noise, harshness or
vibration transmitted into the cabin. Aiding the driving is GMC’s Stabilitrak
stabilizer control.

2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro
Ready for the mud

There was no learning curve
with the hydraulic-assisted brake system that included four-wheel anti-lock
discs and electronic stability assist, which brought the truck to confident
stops. The electric-assisted steering had good road feel with responsiveness
and little body roll in most cornering situations.

Clean Fleet Report
didn’t have the opportunity to do any off-roading, nor did we encounter any wet
or sloppy weather during our week driving through Southern California. But from
the standard and optional equipment, we can tell the Sierra AT4 would handle
pretty much whatever you threw at it, short of serious rock crawling. Our
Sierra AT4 had the X31 off-road suspension, a two-inch lift, Rancho monotube
shocks, skidplates and mud-rated Goodyear Wrangler DuraTrac 275/65 tires
mounted on 18-inch machined aluminum wheels with dark grey accents.

The dash has controls for 2WD,
4WD and Auto 4WD. The first two are self-explanatory, but the latter is a nice
feature as it automatically sends torque to the front tires if the system
senses any tire slippage. This is not an AWD system, but pretty close, that
offers a sense of security and confidence in slippery or sloppy road
conditions. Our Sierra AT4 also was equipped with the trailering package that
included a trailer brake controller, jackknife alert and trailer electrical

Upscale Interior

2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro
A high-end look

The well laid-out interior uses
upgraded materials, many of which rival the high-end GMC Denali. Clean Fleet
Sierra AT4 had an attractive two-tone interior of Jet Black with
Kalahari accents. The leather-trimmed seats were firm and comfortable with the
heated, ventilated, 10-way power front buckets (the driver gets memory) separated
by a center console large enough to hold a laptop. The 60/40 folding rear seat,
with storage compartments in the back and under the seat, was heated for the
outbound passengers and can easily hold three full-size adults. The power rear
sliding window and power sunroof were nice features, along with the wireless
charger for mobile phones, dual zone climate control and leather-wrapped,
heated steering wheel with audio and cruise controls.

The standard rear vision camera
provided clear, wide images on the 8.0-inch color touchscreen monitor with
up-to 15 camera views, including surround vision, two trailer and one bed view.
The screen also is home for navigation and the seven-speaker Bose Premium Sound
System with FM/HD AM radio, wireless Apple CarPlay, Android Auto and SiriusXM.
Bluetooth handled voice communication for hands-free phone, audio and OnStar.
Multiple front and rear USB ports and an auxiliary power outlet kept everything
charged and ready to go. The dash gauges were easy to read, and the radio
passed the Clean Fleet Report minimum driver safety test as it had
volume and channel selection knobs. About those radio knobs and the climate
control wheels: they are constructed using a cheap-feeling chromed plastic.
These were the only drawbacks to this fine interior, but certainly not a deal

2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro
A signature stitch

A note regarding OnStar:
a simple push of a button connects you with a friendly General Motors
representative to handle emergencies, directions and general assistance to make
your driving experience safer and more enjoyable. This is one area where GM is
the industry leader, and after the trial service plan expires, it is well worth

Another convenience was the 4G LTE
Wi-Fi Hotspot that can connect multiple devices and has a 50-foot range. If you
are packing the family for a road trip, then the Wi-Fi is a must to keep the
backseat crew happy, occupied and quiet.

Bold Design

Fleet Report

was driving the Sierra 1500 AT4 with the CarbonPro trim line. CarbonPro
designates the box is made of weight-reducing carbon fiber where the standard
steel inner panels and floor are replaced with a lightweight, purpose-designed
carbon fiber composite that offers best-in-class dent, scratch and corrosion
resistance. This is a big step in box design, so expect to see this material
used soon elsewhere on other General Motor’s trucks. The CarbonPro package was
enhanced by the Onyx Black paint with a tasteful use of chrome and red tow
hooks poking out from under the front fascia. The grille, with its LED
reflector high-intensity headlights, C-shaped daytime running lights and fog
lights did not present as massive as front ends found on other trucks. The
power-adjustable and heated exterior mirrors provided excellent rear visibility
and were quiet going through the wind.

A bed extender

The Sierra 1500 AT4 came with the GMC MultiPro tailgate, which has six functions that make it extremely useful. Excellent access to the box is made possible by the tailgate that drops down in one piece and has two built-in load stops; has a section that drops so you can stand even closer to the box and your cargo; a section that drops to create a full-width step that can handle 375 pounds; and, lastly, for a cool factor, the gate has a built-in Kicker audio system that runs off a flash drive.

2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro
An extra step

box has LED lighting and 12 fixed tie-down rings with the corner rings rated at
500 pounds. The 120-volt power outlet is a useful feature, as was the running
board step and the corner steps on the rear bumper outer edges. The tailgate
can also be power-operated down by the key fob or a piano switch on the

Safety and Convenience

The 2021 Sierra AT4 has front
and side curtain airbags
, electronic
stability control with rollover mitigation, trailer sway control and hill start
assist and a tire pressure monitoring system. The standard advanced driver
assistance systems (ADAS) include lane change and blind zone alert, rear cross
traffic alert and front and rear parking assist. The Driver Alert Package II
($1,095 option) included automatic emergency braking and forward collision
alert, lane keep assist and departure warning, front pedestrian braking and a
vibrating driver’s seat which lets you know something about your driving isn’t
just right. Also available on the Sierra was the Teen Driver
safety system, which helps inexperienced drivers develop safe driving habits.

2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro
A versatile rear seat

The multi-color 15-inch diagonal
head-up display was both a convenience and safety feature. Clean Fleet
feels a HUD should be standard on all vehicles if auto manufacturers
and the government are serious about reducing distracted driving.

To aid in rear visibility, the
rear view mirror can act like a conventional mirror, but also as a high
definition camera. The camera mode takes some getting used to, as the
perspective is different, showing a wider view. I found it especially helpful
when parking, used in conjunction with the multiple rearview cameras.

The 2021 Sierra has earned a US Government National
Highway Traffic Safety Administration (NHTSA)
4 out of 5 Stars Overall Vehicle Score. The Insurance
Institute for Highway Safety (IIHS)
has given the Sierra an overall Good rating.

Pricing and Warranties

Clean Fleet Report’s
2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro had a base MSRP of
$53,800. With $10,125 in options and the $1,595
destination charge, the total came to $65,520.

The 2021 GMC Sierra comes with these warranties:

  • Bumper-To-Bumper – Three years/36,000
  • Powertrain – Five years/100,000 miles
  • Roadside Assistance – Five years/100,000
  • Corrosion – Three years/36,000 miles
  • Rust-Through – Six years/100,000 miles
  • Maintenance – First Visit

Observations: 2021 GMC Sierra 1500 Duramax 4WD Crew Cab
AT4 CarbonPro

Is the 2021 GMC Sierra 1500 Duramax the best 1500 pickup on the market? Talking with “truck guys and gals” and reading truck forums, it seems to be near or at the very top. Obviously, if you need a truck for a specific reason, say towing a large weight or the ability to go serious rock climbing, then the 2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro may not be for you.

2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro
All the bases are covered

However, if you are looking for
comfort, versatility, great looks, a very accommodating and large interior,
some innovative features and, of course, excellent fuel economy, then this may
be the truck for you.

It used to be
that diesel engines were only found in heavy-duty trucks. No more, as they are
becoming more prevalent. The 3.0L Duramax turbo diesel is the most efficient
engine offered in any GMC Sierra pickup. It falls between the 4.3L V6, 5.3L V8 and
6.2L V8 gasoline engines, offering a smooth power plant that can flirt with 30
miles to the gallon on the highway.

sure to opt-in to the Clean
Fleet Report
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Story by John Faulkner. Photos by John Faulkner and GMC.

[See image gallery at]

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Clean Fleet Report is loaned free test vehicles
from automakers to evaluate, typically for a week at a time. Our road tests are
based on this one-week drive of a new vehicle. Because of this we don’t address
issues such as long-term reliability or total cost of ownership. In addition,
we are often invited to manufacturer events highlighting new vehicles or
technology. As part of these events we may be offered free transportation,
lodging or meals. We do our best to present our unvarnished evaluations of
vehicles and news irrespective of these inducements.

Our focus is on vehicles that offer the best fuel economy in
their class, which leads us to emphasize electric cars, plug-in hybrids,
hybrids and diesels. We also feature those efficient gas-powered vehicles that
are among the top mpg vehicles in their class. In addition, we aim to offer
reviews and news on advanced technology and the alternative fuel vehicle
market. We welcome any feedback from vehicle owners and are dedicated to providing
a forum for alternative viewpoints. Please let us know your views at

The post Road Test: 2021 GMC Sierra 1500 Duramax 4WD Crew Cab AT4 CarbonPro first appeared on Clean Fleet Report.

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