The GMC Sierra 1500 III, specifically the Extended Cab Long Box configuration with the 6.2-liter Vortec V8 engine and automatic transmission, was produced from 2010 to 2013. This variant represented a significant offering within the GMT900 platform, GMC’s full-size pickup truck line. Positioned as a robust work and family vehicle, it catered to buyers needing substantial towing and hauling capacity combined with passenger space. The 6.2L engine option was a step up in performance from the base engines, appealing to those who required more power for demanding tasks. This model year marked a transition period for GMC, incorporating updated styling and technology while maintaining the traditional truck attributes valued by its customer base.
Technical Specifications
| Brand | GMC |
| Model | Sierra 1500 |
| Generation | Sierra 1500 III (GMT900) Extended Cab Long Box |
| Type (Engine) | 6.2 Vortec V8 (403 Hp) Automatic FlexFuel |
| Start of production | 2010 |
| End of production | 2013 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 5 |
| Doors | 2 |
| Fuel consumption (urban) | 18.1 l/100 km (13 US mpg) |
| Fuel consumption (extra urban) | 12.4 l/100 km (19 US mpg) |
| Fuel Type | Petrol / Ethanol – E85 |
| Power | 403 Hp @ 5700 rpm |
| Torque | 565 Nm @ 4300 rpm (416.72 lb.-ft. @ 4300 rpm) |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | L9H |
| Engine displacement | 6162 cm3 (376.03 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 103.25 mm (4.06 in.) |
| Piston Stroke | 92 mm (3.62 in.) |
| Compression ratio | 10.5:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | OHV |
| Engine oil capacity | 5.7 l (6.02 US qt | 5.02 UK qt) |
| Coolant capacity | 11.9 l (12.57 US qt | 10.47 UK qt) |
| Max. weight | 3130 kg (6900.47 lbs.) |
| Trunk (boot) space – maximum | 2138 l (75.5 cu. ft.) |
| Fuel tank capacity | 128 l (33.81 US gal | 28.16 UK gal) |
| Length | 6325 mm (249.02 in.) |
| Width including mirrors | 2031 mm (79.96 in.) |
| Height | 1870 mm (73.62 in.) |
| Wheelbase | 4001 mm (157.52 in.) |
| Front track | 1732 mm (68.19 in.) |
| Rear (Back) track | 1702 mm (67.01 in.) |
| Ride height (ground clearance) | 230 mm (9.06 in.) |
| Minimum turning circle | 15.6 m (51.18 ft.) |
| Approach angle | 15.3° |
| Departure angle | 24° |
| Ramp-over angle | 19.6° |
| Drivetrain Architecture | Rear wheel drive |
| Number of gears and type of gearbox | 6 gears, automatic transmission Hydra-Matic |
| Front suspension | Independent coil spring |
| Rear suspension | Rigid axle suspension, Leaf spring |
| Front brakes | Ventilated discs, 330.2×30 mm |
| Rear brakes | Disc, 342.9×20 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Electric Steering |
| Tires size | 265/70 R17 |
| Wheel rims size | 7.5J x 17 |
Powertrain & Engine Architecture
The heart of this Sierra 1500 variant is the 6.2-liter Vortec L9H V8 engine. This engine is a member of the Vortec family, known for its robust construction and relatively simple design. It features a cast iron block with aluminum cylinder heads, contributing to its durability. The engine utilizes a multi-port fuel injection system, delivering fuel directly to each cylinder for efficient combustion. The overhead valve (OHV) valvetrain, while traditional, proved reliable and cost-effective. The 6.2L engine’s FlexFuel capability allowed it to run on gasoline or a blend of up to 85% ethanol (E85), offering some flexibility at the pump. The Hydra-Matic 6L80 six-speed automatic transmission was paired with this engine. This transmission offered smooth shifting and helped optimize fuel economy and performance. The transmission’s gear ratios were tuned to provide a balance between towing capability and everyday drivability.
Driving Characteristics
The 6.2L V8, producing 403 horsepower and 417 lb-ft of torque, delivered strong acceleration and ample power for towing and hauling. Compared to the standard 4.8L or 5.3L V8 options, the 6.2L provided a noticeable increase in performance. While not as fuel-efficient as the smaller engines, the 6.2L offered a more confident driving experience, especially when loaded or towing. The automatic transmission shifted smoothly, and the six-speed design helped keep the engine in its optimal power band. The extended cab configuration provided additional rear seat space, making it suitable for families or crews. However, the longer wheelbase and increased weight compared to a regular cab model did slightly impact maneuverability.
Equipment & Trim Levels
The Extended Cab Long Box 6.2L Sierra 1500 typically came standard with features like air conditioning, power windows and locks, a basic audio system, and cloth upholstery. Higher trim levels, such as the SLT and Denali, added features like leather upholstery, heated seats, a premium audio system, navigation, and more advanced safety features. Optional extras included a sunroof, upgraded wheels, and various towing packages. The interior design was functional and durable, prioritizing practicality over luxury, although higher trims offered a more refined experience.
Chassis & Braking
The GMT900 platform utilized a body-on-frame construction, providing a robust and durable chassis. The front suspension featured independent coil springs, while the rear suspension employed a traditional leaf spring setup. This configuration was designed to handle heavy loads and provide a comfortable ride. The braking system consisted of ventilated discs up front and discs in the rear, providing adequate stopping power for the truck’s weight. An Anti-lock Braking System (ABS) was standard, enhancing safety during emergency braking situations.
Market Reception & Comparison
The 6.2L Sierra 1500 was generally well-received by critics and consumers alike. It was praised for its powerful engine, comfortable ride, and spacious interior. However, its fuel economy was a common criticism, especially compared to newer, more fuel-efficient trucks. Compared to the 5.3L V8, the 6.2L offered a significant performance boost but came at a higher price point. The 6.2L was often seen as a competitor to the Ford F-150 with the 6.2L engine and the Ram 1500 with the 5.7L Hemi V8.
Legacy
The 6.2L Vortec V8 in the GMT900 Sierra 1500 has proven to be a relatively reliable powertrain. While like any vehicle, maintenance is key, these engines are known for their longevity when properly cared for. In the used car market, these trucks remain popular choices for those seeking a capable and durable full-size pickup. The 6.2L engine commands a premium over the smaller engine options due to its performance and desirability. The GMT900 platform, while superseded by newer generations, continues to be valued for its simplicity and ruggedness.
