The 2015 GMC Sierra 1500 offered three EcoTec3 engines: a 4.3-liter V6, a 5.3-liter V8, and a 6.2-liter V8.
These engines are part of GM's EcoTec3 family and were paired with six- or eight-speed automatic transmissions. Availability depended on trim level and drivetrain configuration.
Engine options
Below are the available engines for the 2015 Sierra 1500, listed with their approximate outputs.
- 4.3L EcoTec3 V6 — 285 hp and 305 lb-ft of torque
- 5.3L EcoTec3 V8 — 355 hp and 383 lb-ft of torque
- 6.2L EcoTec3 V8 — 420 hp and 460 lb-ft of torque
Concluding: The 4.3L and 5.3L engines were typically paired with a 6-speed automatic transmission, while the 6.2L typically used an 8-speed automatic, with EcoTec3 technologies like direct injection, variable valve timing, and Active Fuel Management across the lineup.
Performance and technology
The EcoTec3 engine family in the Sierra 1500 combines power with efficiency-focused features such as direct injection, variable valve timing, and active fuel management. This blend supports a range of use cases from everyday driving to towing and payload tasks, with more substantial performance coming from the larger V8 options.
Transmission pairing by engine
- 4.3L V6 and 5.3L V8: typically paired with a 6-speed automatic transmission
- 6.2L V8: paired with an 8-speed automatic transmission
Note: Availability and exact transmission mapping varied by trim, cab/configuration, and 2WD/4WD configuration.
Summary
The 2015 GMC Sierra 1500’s engine lineup consisted of three EcoTec3 options—the 4.3L V6, the 5.3L V8, and the 6.2L V8—offering a balance of efficiency and capability. Transmission choices aligned with engine selection, with six-speed automatics for the smaller engines and an eight-speed automatic for the 6.2L V8, delivering a flexible setup for different needs and trims.