2018 GMC Sierra — Full Specifications
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The 2018 GMC Sierra 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. A hybrid version is also listed by EPA (5.3L 8-cyl), returning around 24 mpg (UK) combined. Owners often keep a GMC Sierra workshop manual to hand for servicing and repairs.
Related 2018 listings: GMC Sierra C15, GMC Sierra K15.
Compared with the 2017 GMC Sierra: 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 | 3 / 10 (10 = lowest emissions) |
| EPA Est. Annual Fuel Cost | $3,350 (15,000 mi/yr, US prices) |
Engine & Transmission Options
EPA lists 12 configurations for the 2018 GMC Sierra 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 | 4-Wheel Drive | 23 | 19 (17/22) | 295 | $3,550 |
| 4.3L 6-cyl | Automatic 6-spd | Rear-Wheel Drive | 24 | 20 (18/24) | 278 | $3,350 |
| 5.3L 8-cyl | Automatic 6-spd | 4-Wheel Drive | 20 | 17 (15/19) | 325 | $3,950 |
| 5.3L 8-cyl | Automatic 6-spd | 4-Wheel Drive | 22 | 18 (16/22) | 304 | $3,700 |
| 5.3L 8-cyl | Automatic 6-spd | Rear-Wheel Drive | 23 | 19 (16/23) | 295 | $3,550 |
| 5.3L 8-cyl | Automatic 6-spd | Rear-Wheel Drive | 23 | 19 (16/23) | 295 | $3,550 |
| 5.3L 8-cyl (Hybrid) | Automatic 8-spd | 4-Wheel Drive | 22 | 18 (16/21) | 304 | $3,700 |
| 5.3L 8-cyl | Automatic 8-spd | 4-Wheel Drive | 20 | 17 (15/20) | 324 | $3,950 |
| 5.3L 8-cyl (Hybrid) | Automatic 8-spd | Rear-Wheel Drive | 24 | 20 (18/24) | 278 | $3,350 |
| 5.3L 8-cyl | Automatic 8-spd | Rear-Wheel Drive | 22 | 18 (16/22) | 308 | $3,700 |
| 6.2L 8-cyl | Automatic 8-spd | 4-Wheel Drive | 20 | 17 (15/20) | 326 | $4,850 |
| 6.2L 8-cyl | Automatic 8-spd | Rear-Wheel Drive | 20 | 17 (15/21) | 321 | $4,850 |
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 2018 GMC Sierra
Running Costs: 2018 GMC Sierra
Covering around 8,000 miles a year in a 2018 GMC Sierra 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.
2018 GMC Sierra Safety Ratings (NHTSA)
Recalls & Owner Complaints (NHTSA)
NHTSA lists 12 safety recall campaigns that include the 2018 GMC Sierra (as of 6 October 2026). Most affected areas: Air bags (4), Service brakes (3), Fuel system (1). A campaign often covers several model years or models, so check your own VIN to see whether your car is affected.
- Air bags — campaign 26V325000, reported 21 May 2026. Risk: A detached end cap or inflator rupture can allow compressed gas to escape and project the end cap or fragments of the inflator into the vehicle, increasing the risk of injury.
- Air bags — campaign 26V166000, reported 19 March 2026. Risk: A detached end cap or inflator rupture can allow compressed gas to escape and project the end cap or fragments of the inflator into the vehicle, increasing the risk of injury.
- Air bags — campaign 25V432000, reported 26 June 2025. Risk: A detached end cap or inflator rupture can allow compressed gas to escape and project the end cap or fragments of the inflator into the vehicle, increases the risk of injury or crash.
- Air bags — campaign 24V756000, reported 10 October 2024. 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.
Showing the 4 most recent of 12 campaigns.
Owners have filed 370 complaints with NHTSA about the 2018 GMC Sierra. The most-reported areas are Power train (136), Engine (81), Electrical system (52). Complaints include 10 reported crashes, 3 reported fires, 6 reported injuries. That is close to the median of 479 complaints across the 17 GMC Sierra model years in our data.
Used-buyer checklist for the 2018 GMC Sierra
Based on where NHTSA recalls and owner complaints cluster for this model year, these are the areas worth checking before you buy:
- Transmission & drivetrain (136 owner complaints) — On the test drive, watch for hesitation, jerking or slipping between gears and ask for transmission service history.
- Engine (81 owner complaints) — Listen for unusual noise on a cold start, check for warning lights and ask for the service records.
- Brakes (3 recall campaigns · 50 owner complaints) — Brake firmly from speed and look for pulling, vibration or a soft pedal; ask for brake service history.
- Electrical system (52 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 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 2018 GMC Sierra's 24 mpg is 2 mpg below that make average.
Of the 17 GMC Sierra model years we cover, the 2018 ranks 9th for combined fuel economy on its best configuration (24 mpg UK combined, against a high of 31 mpg). See every GMC Sierra 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 2018 GMC Sierra
Frequently Asked Questions
What engine does the 2018 GMC Sierra have?
EPA lists 3 engines for the 2018 GMC Sierra: 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 2018 GMC Sierra?
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. The hybrid version returns around 24 mpg (UK) combined.
How much does the 2018 GMC Sierra 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 2018 GMC Sierra have a good safety rating?
It holds an overall NHTSA rating of 5 stars, with 5 stars for frontal crash protection.
Does the 2018 GMC Sierra have any recalls?
NHTSA lists 12 safety recall campaigns that include the 2018 GMC Sierra (as of 6 October 2026). Most affected areas: Air bags (4), Service brakes (3), Fuel system (1). 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 2018 GMC Sierra?
Among the 370 owner complaints filed with NHTSA, the most-reported areas are Power train (136 complaints), Engine (81 complaints), Electrical system (52 complaints). Complaints are unverified owner reports, not confirmed defects, and raw counts rise with how many cars were sold.
Is the GMC Sierra'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.