The GMC Sierra 1500 III, specifically the Extended Cab Long Box configuration with the 5.3-liter Vortec V8 engine and automatic transmission, represents a significant iteration in GMC’s full-size pickup truck lineage. Produced from 2010 through 2013 as part of the GMT900 generation, this variant aimed to balance capability, comfort, and fuel efficiency within the highly competitive American truck market. It served as a popular choice for both personal and commercial use, offering a versatile platform for work and family needs. This particular trim level occupied a middle ground in the Sierra 1500 lineup, offering more power and features than the base models, but remaining more accessible than the fully-loaded Denali trims.
Technical Specifications
| Brand | GMC |
| Model | Sierra 1500 |
| Generation | Sierra 1500 III (GMT900) Extended Cab Long Box |
| Type (Engine) | 5.3 Vortec V8 (315/326 Hp) Automatic FlexFuel |
| Start of production | 2010 |
| End of production | 2013 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Pick-up |
| Seats | 6 |
| Doors | 2 |
| Fuel consumption (urban) | 15.7 l/100 km (15 US mpg, 18 UK mpg, 6.4 km/l) |
| Fuel consumption (extra urban) | 11.2 l/100 km (21 US mpg, 25.2 UK mpg, 8.9 km/l) |
| Fuel Type | Petrol / Ethanol – E85 |
| Weight-to-power ratio | 7.6 kg/Hp, 131.9 Hp/tonne |
| Weight-to-torque ratio | 5.3 kg/Nm, 190.1 Nm/tonne |
| Power | 315 Hp @ 5200 rpm |
| Power per litre | 59.1 Hp/l |
| Power (Ethanol – E85) | 326 Hp @ 5300 rpm |
| Power per litre (Ethanol – E85) | 61.2 Hp/l |
| Torque | 454 Nm @ 4400 rpm (334.85 lb.-ft. @ 4400 rpm) |
| Torque (Ethanol – E85) | 472 Nm @ 4400 rpm |
| Maximum engine speed | 6000 rpm |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | LMG |
| Engine displacement | 5328 cm3 (325.13 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 96.01 mm (3.78 in.) |
| Piston Stroke | 91.95 mm (3.62 in.) |
| Compression ratio | 9.9:1 |
| 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 | 14.1 l (14.9 US qt | 12.41 UK qt) |
| Kerb Weight | 2388 kg (5264.64 lbs.) |
| Max. weight | 3130 kg (6900.47 lbs.) |
| Max load | 742 kg (1635.83 lbs.) |
| Trunk (boot) space – maximum | 2138 l (75.5 cu. ft.) |
| Fuel tank capacity | 128 l (33.81 US gal | 28.16 UK gal) |
| Permitted trailer load with brakes (12%) | 4173 kg (9199.89 lbs.) |
| 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 (turning diameter) | 15.6 m (51.18 ft.) |
| Approach angle | 15.3° |
| Departure angle | 24° |
| Ramp-over (brakeover) angle | 19.6° |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | 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 | Disc, 330×30 mm |
| Rear brakes | Drum, 295×60 mm |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Electric Steering |
| Tires size | 245/70 R17 |
| Wheel rims size | 7.5J x 17 |
Powertrain & Engine Architecture
At the heart of this Sierra 1500 variant lies the 5.3-liter (325.13 cubic inch) Vortec 5300 V8 engine, designated with the code LMG. This engine is a member of the Vortec family, known for its robust construction and relatively simple design. It features a cast iron block and aluminum cylinder heads, utilizing a 9.9:1 compression ratio and a two-valve-per-cylinder overhead valve (OHV) valvetrain. Fuel delivery is managed by a multi-port fuel injection system. The engine’s capability is further enhanced by its FlexFuel compatibility, allowing it to run on gasoline or a blend of up to 85% ethanol (E85). When running on E85, the engine produces slightly more power – 326 horsepower – due to ethanol’s higher octane rating. The engine is mated to a six-speed Hydra-Matic automatic transmission, providing smooth shifting and adequate gear ratios for both towing and everyday driving. The transmission was chosen for its durability and ability to handle the engine’s torque output.
Driving Characteristics
The 5.3L V8 with the six-speed automatic delivers a comfortable and capable driving experience. While not as quick as the available 6.2L V8, the 5.3L provides ample power for most tasks, including towing and hauling. The automatic transmission is well-tuned, offering smooth shifts and responsive downshifts when needed. The gear ratios are optimized for both fuel economy and towing performance. In real-world conditions, acceleration from 0 to 60 mph typically takes around 7.5-8.5 seconds. The extended cab configuration adds some weight, slightly impacting performance compared to the regular cab models. The ride quality is generally comfortable, thanks to the independent front suspension and leaf spring rear suspension, although the ride can become somewhat bumpy when the bed is unloaded.
Equipment & Trim Levels
The Extended Cab Long Box 5.3L Automatic Sierra 1500 typically came standard with features like air conditioning, power windows and locks, a basic audio system, and cloth upholstery. Extended cab models offered a rear bench seat, increasing passenger capacity to six. Popular optional extras included a premium audio system, leather upholstery, power-adjustable seats, a navigation system, and various towing packages. Trim levels varied, but generally included SLE and SLT packages, with SLT offering more luxurious appointments and features.
Chassis & Braking
The GMT900 Sierra 1500 utilizes a body-on-frame construction, providing a robust and durable platform. The front suspension features independent coil springs, while the rear suspension employs a traditional leaf spring setup. This configuration balances ride comfort with load-carrying capacity. Braking duties are handled by disc brakes up front and drum brakes in the rear. Anti-lock Braking System (ABS) is standard. The steering system is a rack-and-pinion setup with electric power steering, providing responsive and precise handling.
Market Reception & Comparison
The 2010-2013 GMC Sierra 1500 with the 5.3L V8 and automatic transmission was generally well-received by critics and consumers. It was praised for its comfortable ride, spacious interior, and capable towing capacity. Fuel economy, however, was a common criticism, with the 5.3L V8 achieving around 15 mpg in the city and 21 mpg on the highway. Compared to the 4.8L V8 models, the 5.3L offered significantly more power and torque, making it a better choice for those who frequently tow or haul heavy loads. Compared to the 6.2L V8, the 5.3L was more affordable and offered slightly better fuel economy, although at the expense of some performance.
Legacy
The GMT900 Sierra 1500, particularly the 5.3L V8 variant, has proven to be a relatively reliable truck in the used car market. The Vortec 5300 engine is known for its durability, and with proper maintenance, can easily exceed 200,000 miles. Common issues include oil leaks, sensor failures, and occasional transmission problems. However, these issues are generally not catastrophic and can be addressed with reasonable repair costs. Today, these trucks remain popular choices for those seeking a capable and affordable full-size pickup, offering a good balance of power, comfort, and reliability.
