Is the 2018 GMC Terrain a bad year?
226 owner complaints to NHTSA. Transmission complaints: 42, 3.8× a quiet Terrain year.
Keep it, but watch the transmission
Half of the transmission complaints for this year were filed at 3k–59k miles, where you are now.
The verdict moves with mileage: the same car reads differently at 30,000 and at 150,000 miles.
What 2018 Terrain owners report, by mileage
Each system owners named in five or more complaints, with the mileage range where the middle half of those complaints were filed. Read at 10,000 miles.
| SYSTEM | COMPLAINTS | MIDDLE HALF FILED AT | TYPICAL US REPAIR BILLS |
|---|---|---|---|
| Transmission and drivetrainSTANDS OUT | 42 (19%) | 3k–59k miles · around this mileage | CV axle / CV joint replacement (one side) $300–$1,500 · Automatic transmission replacement $2,500–$7,000 |
| BrakesSTANDS OUT | 83 (37%) | 32k–96k miles · ahead | Brake pad replacement (one axle) $115–$390 · Brake pads and rotors replacement (one axle) $200–$1,084 |
| Engine | 56 (25%) | 9k–94k miles · around this mileage | Valve cover gasket replacement $110–$500 · Timing chain replacement $1,000–$4,000 |
| Electrical system | 35 (15%) | 2k–41k miles · around this mileage | 12-volt battery replacement $100–$400 · Starter motor replacement $350–$1,200 |
| Fuel system | 17 (8%) | too few with a mileage | — |
| Air bags | 14 (6%) | too few with a mileage | — |
| Collision avoidance | 8 (4%) | too few with a mileage | — |
| Speed control | 8 (4%) | too few with a mileage | — |
| Stability control | 7 (3%) | too few with a mileage | — |
| Steering | 7 (3%) | too few with a mileage | — |
| Visibility and wipers | 5 (2%) | too few with a mileage | — |
Bills are typical US ranges from the sources named in the tool (J.D. Power, Kelley Blue Book, CarParts.com and others), printed only for systems that stand out or sit at or ahead of 10,000 miles. Not a quote.
What owners reported alongside their complaints
Of 226 complaints: 14 mention a crash · 1 mentions a fire · 7 report an injury · 21 say the car was towed.
32 complaints were filed in the last 12 months, the newest in Oct 2026.
Counts of what owners wrote in their complaints, not verified by anyone.
In owners' own words
Transmission fails to down shift after accelerating in traffic. RPM legal 2200 RPM at 40 MPH for over a mile before dropping to correct 1200 RPM for that speed.
First issue with the vehicle was a separation of the dash near and around the passenger side airbag. Unknown at this time if the airbag has been compromised.
My auto started leaking some kind of oil.not sure what kind but I can see accumulation on driveway concrete pad.
Unedited excerpts from complaints filed with NHTSA, chosen by mileage (nearest 10,000 miles), not by content. Unverified.
Recalls for the 2018 GMC Terrain: 5
The start/stop accumulator endcap may have missing bolts. Missing bolts on the start-stop accumulator endcap could result in a transmission oil leak and may progress to a loss of propulsion, increasing the risk of a crash.
The rear brake caliper pistons may have an insufficient coating causing gas pockets to form, potentially reducing rear brake performance. A reduction of braking performance can increase the risk of a crash.
The high pressure fuel pump may detach from its mounting flange, possibly resulting in the pump damaging the high pressure fuel line. A damaged fuel line can create a fuel leak, increasing the risk of a fire.
The sensing diagnostic module (SDM) that senses a crash and deploys the necessary air bags may not power down correctly when the vehicle is shut off, causing it to be inoperative when the vehicle is restarted. If the SDM becomes inoperative, it will not detect a crash or command the necessary air bag deployment, increasing the risk of injury in the event of a crash.
The right front intermediate driveshaft may fracture and separate while driving. If the front right intermediate drive shaft assembly separates while driving, the vehicle will lose propulsion, increasing the risk of a crash.
A recall may cover only some cars of a model year; the campaign size counts every model and year it lists. Enter your VIN at nhtsa.gov/recalls: dealers fix open recalls free.
Service bulletins from GMC: 516
Repair instructions GMC sent its dealers for symptoms seen in the shop on the 2018 GMC Terrain. Ask a dealer or mechanic for a bulletin by its number.
Normal transmission shift condition and the delay in throttle response when the throttle plate is opened rapidly and advises the customer that it is normal…
Correct a customer concern of Vehicle Will Not Lock and Unlock (Loss of Active Functions) Crank or Start (Loss of Passive Functions) with DTC P0513 Set
Guidelines to replace Oil Cooler, Oil Cooler Lines and Oil Tank if the engine was replaced where large amounts of debris has flowed throughout the oiling system
Rotational Clicking Noise Heard After Engine Shut Down may be normal characteristics of the vehicle
Neighbouring years
2017 Terrain: 135 complaints, keep it, but watch the engine · 2019 Terrain: 187 complaints, keep it, but watch the transmission.
Every GMC Terrain year
2010 · 2011 · 2012 · 2013 · 2014 · 2015 · 2016 · 2017 · 2018 · 2019 · 2020 · 2021 · 2022 · 2023 · 2024 · 2025 · 2026 · All Terrain years side by side
Other GMC models: GMC Acadia · GMC Canyon · GMC Denali · GMC Envoy · GMC Envoy XL · GMC Envoy Xuv · GMC Jimmy · GMC Safari · GMC Savana · GMC Sierra · GMC Sierra 1500 · GMC Sierra 2500 · GMC Sierra 3500 · GMC Sierra Denali · GMC Sonoma · GMC Yukon · GMC Yukon Denali · GMC Yukon Denali XL · GMC Yukon XL · GMC Yukon XL 1500. All makes and models.
Questions
Is the 2018 GMC Terrain a bad year?
226 owner complaints to NHTSA. Transmission complaints: 42, 3.8× a quiet Terrain year. At 10,000 miles the tool says: Keep it, but watch the transmission. Half of the transmission complaints for this year were filed at 3k–59k miles, where you are now.
What are the most common problems with the 2018 GMC Terrain?
By owner complaints to NHTSA: transmission and drivetrain (42), brakes (83), engine (56), electrical system (35), fuel system (17). Half of the transmission complaints were filed between 3k–59k miles.
How many recalls does the 2018 GMC Terrain have?
5 recall campaigns list this model year: Transmission and drivetrain (NHTSA 20V-668), Brakes (NHTSA 18V-576), Fuel system (NHTSA 18V-358), Air bags (NHTSA 18V-340) and more. A recall may cover only some cars; check by VIN at nhtsa.gov/recalls.
Method: counts of unverified owner complaints filed with NHTSA, compared only with other years of the same model (sales volumes are unknown, so no failure rate is computed). A system stands out at 40+ complaints and at least twice the model's quiet (lower-quartile) year, or twice the share across every vehicle of that model year. The mileage range is the 25th to 75th percentile of the mileages owners reported. Data received by NHTSA through November 5, 2026. Repair prices are typical US ranges from named sources, not quotes. Not a diagnosis and not financial advice. PulsCar is not affiliated with NHTSA. Check this car at your own mileage.