2015 GMC Sierra C15 — Full Specifications
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The 2015 GMC Sierra C15 is a pickup offered with 3 engines (4.3L 6-cyl, 5.3L 8-cyl, 6.2L 8-cyl). Its most fuel-efficient configuration returns around 24 mpg (UK) / 20 mpg (US EPA) combined, with 20–24 mpg (UK) across all configurations. Owners often keep a GMC Sierra C15 workshop manual to hand for servicing and repairs.
Related listing: see also the 2015 GMC Sierra page for the base Sierra listing, which may cover additional engines and body styles.
Compared with the 2014 GMC Sierra C15: Fuel economy is essentially unchanged at around 24 mpg (UK) combined. The engine line-up listed by EPA is unchanged. It carries the same 5★ overall NHTSA rating.
Full Specifications
| Engine (most efficient) | 4.3L 6-cyl |
|---|---|
| Engine options | 4.3L 6-cyl · 5.3L 8-cyl · 6.2L 8-cyl |
| Transmission (most efficient) | Automatic 6-spd |
| Fuel Type | Regular Gasoline |
| Powertrain | Conventional |
| Drive | Rear-Wheel Drive |
| Body Style | Pickup |
| Fuel Economy (UK) | 24 combined / 22 urban / 29 extra-urban mpg |
| Fuel Economy (US EPA) | 20 combined / 18 city / 24 highway mpg |
| CO₂ Emissions | 278 g/km |
| EPA Greenhouse Gas Score | 4 / 10 (10 = lowest emissions) |
| EPA Est. Annual Fuel Cost | $3,350 (15,000 mi/yr, US prices) |
Engine & Transmission Options
EPA lists 4 configurations for the 2015 GMC Sierra C15 across 3 engines (4.3L 6-cyl, 5.3L 8-cyl, 6.2L 8-cyl). Combined fuel economy ranges from 17 to 20 mpg (US), or 20 to 24 mpg (UK), depending on engine, transmission and drive. The headline figures at the top of this page describe the most fuel-efficient configuration.
| Engine | Transmission | Drive | MPG (UK) | MPG (US) | CO₂ g/km | Fuel cost / yr |
|---|---|---|---|---|---|---|
| 4.3L 6-cyl | Automatic 6-spd | Rear-Wheel Drive | 24 | 20 (18/24) | 278 | $3,350 |
| 5.3L 8-cyl | Automatic 6-spd | Rear-Wheel Drive | 23 | 19 (16/23) | 297 | $3,550 |
| 5.3L 8-cyl | Automatic 6-spd | Rear-Wheel Drive | 23 | 19 (16/23) | 297 | $3,550 |
| 6.2L 8-cyl | Automatic 8-spd | Rear-Wheel Drive | 20 | 17 (15/21) | 321 | $3,950 |
MPG (US) shows combined, with city/highway in brackets. Highlighted row = the configuration used for the headline figures. Source: US EPA fueleconomy.gov.
Owner Essentials for the 2015 GMC Sierra C15
Running Costs: 2015 GMC Sierra C15
Covering around 8,000 miles a year in a 2015 GMC Sierra C15 at 24 mpg combined, expect roughly 1,515 litres of fuel annually — multiply by your local price per litre for a cost estimate. For US owners, the EPA estimates about $3,350 a year in fuel for the most efficient configuration (15,000 miles, national average prices). Work out exact fuel costs with the fuel cost calculator on 247Calculators.
Convert between MPG and L/100km with the unit converters on 247QuickTools. Not sure what tyre size fits? 247TyreCheck explains tyre sizing.
Only need this car occasionally? See our buy vs rent comparison.
2015 GMC Sierra C15 Safety Ratings (NHTSA)
Recalls & Owner Complaints (NHTSA)
NHTSA lists 9 safety recall campaigns that include the 2015 GMC Sierra C15 (as of 6 October 2026). Most affected areas: Air bags (4), Seat belts (2), Service brakes (2). A campaign often covers several model years or models, so check your own VIN to see whether your car is affected.
- Air bags — campaign 21V504000, reported 1 July 2021. Risk: A separated inflator end cap or inflator rupture can allow compressed gas to escape, resulting in the end cap or other components being propelled into the vehicle, increasing the risk of injury or crash.
- Seat belts — campaign 21V245000, reported 8 April 2021. Risk: A broken pretensioner cable reduces the effectiveness of the driver's seat belt, increasing the risk of injury.
- Air bags — campaign 20V736000, reported 25 November 2020. Risk: If the end cap separates from the inflator, the compressed gas will escape and the end cap can be propelled into the vehicle, increasing the risk of injury or a crash.
- Service brakes — campaign 19V761000, reported 24 October 2019. Risk: Unintended activation of the driveline-protection system will cause unintended braking on the wheel on the opposite side of the failed sensor, causing the vehicle to pull to one side unexpectedly, increasing…
Showing the 4 most recent of 9 campaigns.
Owners have filed 817 complaints with NHTSA about the 2015 GMC Sierra C15. The most-reported areas are Service brakes (231), Exterior lighting (130), Power train (115). Complaints include 29 reported crashes, 10 reported fires, 14 reported injuries. That is well above the median of 304 complaints across the 9 GMC Sierra C15 model years in our data.
Used-buyer checklist for the 2015 GMC Sierra C15
Based on where NHTSA recalls and owner complaints cluster for this model year, these are the areas worth checking before you buy:
- Brakes (2 recall campaigns · 231 owner complaints) — Brake firmly from speed and look for pulling, vibration or a soft pedal; ask for brake service history.
- Lighting (130 owner complaints) — Check every exterior light works and look for moisture inside the lamp housings.
- Transmission & drivetrain (115 owner complaints) — On the test drive, watch for hesitation, jerking or slipping between gears and ask for transmission service history.
- Electrical system (104 owner complaints) — Test every switch, window, light and warning lamp on a test drive, and ask about battery or alternator replacements.
Source: US NHTSA recall and consumer-complaint databases, retrieved 6 October 2026. Complaints are unverified owner reports, not confirmed defects. Check any vehicle by VIN at nhtsa.gov/recalls, and see our guide to checking a used car for recalls.
How It Compares
How does the GMC Sierra C15 compare to similar pickups? Pickups in our database average around 25 mpg (UK) combined — this model sits close to that average, within 1 mpg. Its 278 g/km CO₂ figure is 5 g/km lower than the 283 g/km average for pickups on this site. This comparison is based on 264 pickups in our dataset.
GMC models in our database average about 26 mpg (UK) combined on their most efficient configuration; the 2015 GMC Sierra C15's 24 mpg is 2 mpg below that make average.
Of the 9 GMC Sierra C15 model years we cover, the 2015 is the most economical on its best configuration (24 mpg UK combined). See every GMC Sierra C15 year side by side.
Last updated: · Data: US EPA (fueleconomy.gov) and NHTSA safety ratings 18 July 2026; NHTSA recalls and complaints 6 October 2026; Wikidata & curated EU catalogue 18 July 2026; European generation and engine data from Wikipedia 7 October 2026
Vehicle data sourced from manufacturer specifications. Always verify with your vehicle handbook or a qualified mechanic. This is a reference tool, not professional advice.
Recommended Accessories for the 2015 GMC Sierra C15
Frequently Asked Questions
What engine does the 2015 GMC Sierra C15 have?
EPA lists 3 engines for the 2015 GMC Sierra C15: 4.3L 6-cyl, 5.3L 8-cyl, 6.2L 8-cyl. The most fuel-efficient configuration pairs the 4.3L 6-cyl with a automatic 6-spd.
What is the fuel economy of the 2015 GMC Sierra C15?
The most efficient configuration returns around 24 mpg (UK) combined, or 20 mpg on the US EPA cycle. Across all configurations the UK combined figure runs from 20 to 24 mpg.
How much does the 2015 GMC Sierra C15 cost to fuel per year?
The US EPA estimates about $3,350 a year in fuel for the most efficient configuration, based on 15,000 miles of mixed driving and national average fuel prices. Your own cost will depend on mileage and local prices.
Does the 2015 GMC Sierra C15 have a good safety rating?
It holds an overall NHTSA rating of 5 stars, with 5 stars for frontal crash protection.
Does the 2015 GMC Sierra C15 have any recalls?
NHTSA lists 9 safety recall campaigns that include the 2015 GMC Sierra C15 (as of 6 October 2026). Most affected areas: Air bags (4), Seat belts (2), Service brakes (2). A campaign often covers several model years or models, so check your own VIN to see whether your car is affected.
What are the most common problems reported for the 2015 GMC Sierra C15?
Among the 817 owner complaints filed with NHTSA, the most-reported areas are Service brakes (231 complaints), Exterior lighting (130 complaints), Power train (115 complaints). Complaints are unverified owner reports, not confirmed defects, and raw counts rise with how many cars were sold.
Is the GMC Sierra C15's fuel economy good for a pickup?
It returns around 24 mpg (UK) combined, against a same-body-style average of roughly 25 mpg among the pickups we track.