The Lemon Index2018 GMC Sierra.
The 2018 GMC Sierra is better than average by owner complaints: 139 complaints in its first 3 years and a Lemon Index of 63, where 100 is the average car. Owners complain most about transmission & drivetrain, it has 7 recalls, and it gets 17 to 20 mpg combined. The best GMC Sierra year is 2010.
Before you buy. What matters most for this car.
How serious. Out of 371 owner complaints, owners reported:
Every GMC Sierra year. 2018 is highlighted. Lower is better.
What owners complain about most. From owner complaints to the government.
Share of this year's owner complaints filed with NHTSA, not the share of cars that break. One complaint can name more than one area.
When owners reported problems. From owner complaints to the government.
Most owners who filed a complaint with NHTSA had 8K to 60K miles on the car (155 complaints listed the miles). This shows when people who had a problem reported it, not the odds that your car will have it.
- transmission & drivetrain complaints mostly came at 10K–67K miles
- engine complaints mostly came at 23K–78K miles
- brakes complaints mostly came at 2K–27K miles
Recalls 7
- airbags 2026
The left-side or right-side roof rail air bag (RRAB) inflator end cap may detach from the inflator or the inflator sidewall may rupture.
- airbags 2026
The left or right-side roof rail air bag (RRAB) inflator end cap may detach from the inflator or the inflator sidewall may rupture.
- airbags 2025
The left or right-side roof-rail air bag (RRAB) inflator end cap may detach from the inflator or the inflator sidewall may rupture.
Show all 7 recalls
- airbags 2024
The left or right-side roof-rail air bag (RRAB) inflator end cap may detach from the inflator or the inflator sidewall may rupture.
- brakes 2020
The output of the mechanical vacuum pump can decrease over time, decreasing the amount of vacuum/power brake assist.
- brakes 2019
If a wheel-speed sensor fails, while the vehicle is traveling between 41 and 60 mph in four-wheel or automatic mode, the Electronic-Brake Control Module (EBCM) software may activate the driveline-protection system.
- brakes 2019
The amount of vacuum created by the vacuum pump may decrease over time.
Recall repairs are free at any dealer. A recall only matters if it's still open on that exact car, so check its VIN.
Problems GMC told dealers about
GMC sent dealers 1524 repair notes for this car. The ones about its biggest problems:
- Concern of engine noise and/or a misfire
Ask a seller or mechanic if these were done. Some are free under warranty or a special program.
Safety
Crash test details
| Version | Overall | Front | Side | Rollover |
|---|---|---|---|---|
| GMC Sierra 1500 PU/EC RWD | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★☆ |
| GMC Sierra 1500 PU/EC 4WD | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★☆ |
| GMC Sierra 1500 Hybrid PU/CC RWD | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★☆ |
| GMC Sierra 1500 PU/CC RWD | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★☆ |
| GMC Sierra 1500 PU/CC 4WD | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★☆ |
| GMC Sierra 1500 PU/RC RWD | ★★★★★ | ★★★★★ | ★★★★★ | ★★★★☆ |
Fuel cost and engines
About $3200–4700 a year in fuel (EPA estimate). Engines: 4.3L 6-cyl, 5.3L 8-cyl, 6.2L 8-cyl.
In owners' words
The truck shifts very hard - from what I've read online, GM knows of the issue but will not "fix" the issue -- only 26k miles on the truck
2018 GMC Sierra owner · NHTSA complaint 11282647
More owner reports
Have been to dealer 3 times transmission ruff/slipping on 1-2 shift
NHTSA complaint 11375598
Transmission is slamming violently during shifting, transmission fluid is dark and contaminated. Dealer says-" operating as designed, no issue found" also truck shakes and vibrates violently while driving
NHTSA complaint 11435501
Quick answers
Is the 2018 GMC Sierra reliable?
Yes, better than average by government complaints. It drew 1.6× fewer complaints than average filed with NHTSA in its first 3 years, per car sold (Lemon Index 63; 100 is average, lower is better). The best GMC Sierra year by this measure is 2010.
What are the most common 2018 GMC Sierra problems?
In owner complaints to the government, the parts named most are transmission & drivetrain (35%), engine (14%) and steering (13%). That is the share of complaints, not the share of cars that break.
How many recalls does the 2018 GMC Sierra have?
7 safety recalls (latest: airbags). Recall repairs are free at any dealer; check a specific car's VIN at nhtsa.gov/recalls.
What gas mileage does the 2018 GMC Sierra get?
17 to 20 mpg combined, depending on the engine (EPA estimate).
Is the 2018 GMC Sierra safe?
NHTSA gave it 5 out of 5 stars overall in its best tested version. Ratings differ by body style, and the full table is on the advanced page.
At what mileage do 2018 GMC Sierra problems start?
Half of the owners who gave a mileage reported the problem between 8,300 and 60,800 miles. The middle report was at 30,600 miles, from 155 complaints.
Does the 2018 GMC Sierra have transmission problems?
Transmission and drivetrain issues make up 35% of its owner complaints.
How much does the 2018 GMC Sierra cost in fuel a year?
About $3200 to $4700 a year, by the EPA's current estimate.
What engines does the 2018 GMC Sierra have?
4.3L 6-cyl, 5.3L 8-cyl, 6.2L 8-cyl.
What GMC Sierra year is better than the 2018?
By owner complaints per car sold, the best recent years are 2010, 2012 and 2013.
Lemon Index = safety complaints filed with the U.S. government (NHTSA) in a car's first 3 years, per car sold, against the average car of the same model year. 100 is average; lower is better. A complaint is an owner's report, not a confirmed defect. How it works