2015 GMC Sierra C15 2WD MPG & Specs — Real-World vs EPA, All Trims
Fuel grade varies by trim — see the breakdown below.
Is the 2015 GMC Sierra C15 2WD good on gas?
At up to 20 MPG combined, the 2015 GMC Sierra C15 2WD is better than average for a Standard Pickup Trucks 2WD — that class averages about 17.3 MPG across 1,486 EPA-tested versions, so it's a good pick on fuel for its size.
Real-world MPG vs the EPA number
The EPA figures above come from a standardized dynamometer test, not the open road — real-world MPG typically runs a bit lower depending on your driving, climate and terrain. That's true of every car on this site, old or new.
EPA updated its fuel-economy equations again for model year 2017 — mostly affecting hybrids and turbocharged engines — and recalculated 2011-2016 ratings to match, in some cases 1-2 MPG lower. The number above already reflects that update.
At today's AAA national average price — $3.80/gal for regular gas as of 2026-07-05 — the most efficient trim runs about $3,000/year (roughly $250/month, about $20.00 per 100 miles) at the EPA's assumed 15,000 miles/year, using an estimated 789 gallons a year. We don't estimate a cost-per-fill since exact tank size isn't in the public EPA dataset, but the per-100-mile figure scales to any tank. Current national average gas prices →
2015 GMC Sierra C15 2WD trims & fuel economy
| Trim (engine / transmission) | Fuel | MPG | Fuel/yr (today's price) |
|---|---|---|---|
| 5.3L 8-cyl, Automatic 6-spd, RWD | REGULAR | 19 | $3,000 |
| 6.2L 8-cyl, Automatic 8-spd, RWD | REGULAR | 17 | $3,353 |
| 4.3L 6-cyl, Automatic 6-spd, RWD | FLEX-FUEL | 20 | $3,100 |
| 5.3L 8-cyl, Automatic 6-spd, RWD | FLEX-FUEL | 19 | $3,300 |
2015 GMC Sierra C15 2WD specs
What the EPA test-car listings record for this model year — every combination sold is a row in the trims table above.
| Engine options | 5.3L 8-cyl · 6.2L 8-cyl · 4.3L 6-cyl |
| Transmission | Automatic 6-spd · Automatic 8-spd |
| Drive type | RWD |
| EPA body class | Standard Pickup Trucks 2WD |
| Fuel | Varies by trim |
| Tailpipe CO₂ | 447–517 g/mi |
Other years of the GMC Sierra C15 2WD
Similar cars (Standard Pickup Trucks 2WD)
Cars that take premium · Cheapest cars to fuel · Where fuel grade depends on the trim · Fuel guides
4 trim(s) · EPA FuelEconomy.gov data retrieved 2026-07-24 · fuel prices AAA national average as of 2026-07-05.