The GMC Sierra 1500 V (GMTT1XX) Double Cab AT4 3.0 Duramax TD, produced from 2019 to 2021, represents a significant offering in the increasingly popular full-size pickup truck segment. This variant, equipped with a 3.0-liter Duramax turbocharged diesel engine producing 277 horsepower, was positioned as a premium, capability-focused trim within the Sierra 1500 lineup. It catered to buyers seeking a balance of towing capacity, fuel efficiency, and refined features, particularly in markets where diesel engines are favored for their torque characteristics. The AT4 trim specifically emphasized off-road capability and a more rugged aesthetic compared to lower trims.
Technical Specifications
| Brand | GMC |
| Model | Sierra 1500 |
| Generation | Sierra 1500 V (GMTT1XX) Double Cab |
| Type | AT4 3.0 Duramax TD (277 Hp) 4WD Automatic |
| Start of production | 2019 |
| End of production | 2021 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 10.7 l/100 km (22 US mpg) |
| Fuel consumption (extra urban) | 9 l/100 km (26.1 US mpg) |
| Fuel Type | Diesel |
| Weight-to-power ratio | 8.4 kg/Hp |
| Weight-to-torque ratio | 3.7 kg/Nm |
| Power | 277 Hp @ 3750 rpm |
| Power per litre | 92.3 Hp/l |
| Torque | 623 Nm @ 1500 rpm (459.5 lb.-ft. @ 1500 rpm) |
| Maximum engine speed | 5100 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | LM2 |
| Engine displacement | 3000 cm3 (183.07 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 84 mm (3.31 in.) |
| Piston Stroke | 90 mm (3.54 in.) |
| Compression ratio | 15:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | DOHC |
| Engine oil capacity | 6.6 l (6.97 US qt | 5.81 UK qt) |
| Coolant capacity | 19.1 l (20.18 US qt | 16.81 UK qt) |
| Kerb Weight | 2336 kg (5150 lbs.) |
| Max. weight | 3175 kg (6999.68 lbs.) |
| Max load | 839 kg (1849.68 lbs.) |
| AdBlue tank | 20.3 l (5.36 US gal | 4.47 UK gal) |
| Permitted trailer load with brakes (12%) | 4082 kg (8999.27 lbs.) |
| Length | 5886 mm (231.73 in.) |
| Width including mirrors | 2063 mm (81.22 in.) |
| Height | 1993 mm (78.46 in.) |
| Wheelbase | 3747 mm (147.52 in.) |
| Drivetrain Architecture | All wheel drive (4×4). ICE drives rear wheels, front wheels engaged via clutch. |
| Number of gears and type of gearbox | 10 gears, automatic transmission |
| Front suspension | Independent coil spring |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 330×30 mm |
| Rear brakes | Ventilated discs, 345×20 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Electric Steering |
| Tires size | 255/70 R17; 265/70 R17 |
| Wheel rims size | 8J x 17 |
Introduction
The 2019-2021 GMC Sierra 1500 V Double Cab AT4 3.0 Duramax TD represents GMC’s entry into the increasingly competitive diesel-powered full-size pickup market. Built on the GMTT1XX platform, this generation Sierra aimed to offer a more refined and technologically advanced experience compared to its predecessors. The AT4 trim, introduced alongside this generation, focused on providing enhanced off-road capability and a more aggressive appearance. This particular variant, with its 3.0-liter Duramax engine and ten-speed automatic transmission, was designed to appeal to customers who needed the towing and hauling capacity of a full-size truck, but also desired improved fuel economy and a quieter driving experience compared to gasoline-powered alternatives.
Powertrain & Engine Architecture
The heart of this Sierra variant is the GM LM2 3.0-liter inline-six cylinder diesel engine. This engine utilizes a common-rail direct fuel injection system, delivering fuel at extremely high pressures for optimized combustion. The engine is turbocharged with a variable geometry turbocharger (VGT) and features an intercooler to increase air density and improve power output. The valvetrain employs a double overhead camshaft (DOHC) design with four valves per cylinder, contributing to efficient airflow and improved engine breathing. The engine produces 277 horsepower at 3750 rpm and a substantial 623 Nm (459.5 lb.-ft.) of torque at a low 1500 rpm. This torque output is a key advantage of the diesel engine, providing strong pulling power for towing and hauling. The engine is paired with a sophisticated 10-speed automatic transmission, which helps to optimize fuel efficiency and provide smooth, responsive shifting. This transmission features electronically controlled shifts and a wide gear ratio spread, allowing the engine to operate in its most efficient range more often.
Driving Characteristics
The 3.0-liter Duramax diesel, coupled with the 10-speed automatic, delivers a markedly different driving experience compared to the Sierra’s gasoline engine options. While not as quick off the line as the larger displacement V8s, the diesel provides a broad, flat torque curve that makes it feel strong and capable in everyday driving situations. The ten-speed transmission is well-tuned, offering smooth and almost imperceptible shifts. The gear ratios are optimized for both fuel economy and towing performance. Compared to manual transmission equipped Sierras, the automatic provides a more relaxed and convenient driving experience, particularly in stop-and-go traffic. The AT4 trim’s suspension tuning provides a comfortable ride on paved roads, while still offering sufficient capability for moderate off-road excursions. The engine is relatively quiet for a diesel, but some engine noise is still noticeable, especially during acceleration.
Equipment & Trim Levels
The AT4 trim level came standard with a number of features designed to enhance both comfort and capability. Standard interior features included leather upholstery, heated and ventilated front seats, an 8-inch touchscreen infotainment system with Apple CarPlay and Android Auto compatibility, and a premium audio system. Exterior features included unique AT4 badging, black chrome accents, and off-road tuned suspension. Optional extras included a power sunroof, a rear-seat entertainment system, and a variety of advanced safety features such as adaptive cruise control and lane departure warning. The Double Cab configuration provided ample space for passengers in both rows of seating.
Chassis & Braking
The Sierra 1500 AT4 3.0 Duramax TD utilizes an independent coil spring front suspension and a traditional rigid axle suspension with leaf springs in the rear. This setup provides a good balance of ride comfort and load-carrying capacity. The AT4 trim typically featured heavier-duty shock absorbers and stabilizer bars compared to lower trims. Braking duties are handled by ventilated disc brakes on all four wheels, with larger rotors in the front (330×30 mm) compared to the rear (345×20 mm). The vehicle is equipped with an Anti-lock Braking System (ABS) as standard. The steering system is a rack-and-pinion setup with electric power steering, providing responsive and precise steering feel.
Market Reception & Comparison
The GMC Sierra 1500 AT4 3.0 Duramax TD was generally well-received by automotive critics. Reviewers praised the engine’s strong torque output, smooth shifting transmission, and improved fuel economy compared to gasoline-powered rivals. The AT4 trim’s enhanced off-road capability and rugged styling were also positively noted. Compared to the Sierra 1500 equipped with the 5.3-liter or 6.2-liter V8 engines, the Duramax diesel offered superior fuel economy and towing capacity, but at a higher initial cost. Compared to other diesel-powered full-size trucks, such as the Ram 1500 EcoDiesel, the Sierra offered a competitive combination of performance, features, and price.
Legacy
The LM2 3.0-liter Duramax diesel engine has proven to be a relatively reliable powertrain, although some owners have reported issues with the diesel particulate filter (DPF) system, a common concern with modern diesel engines. The GMTT1XX Sierra 1500, and particularly the AT4 trim, helped to establish GMC as a premium truck brand, offering a compelling alternative to Chevrolet and Ford. On the used car market, these Sierras hold their value reasonably well, particularly those in good condition with low mileage. The combination of capability, comfort, and fuel efficiency continues to make this variant a desirable choice for truck buyers seeking a versatile and capable full-size pickup.
