Large SUV · 2014–2021 cars
Mercedes-Benz GLS reliability
The Mercedes-Benz GLS fails 11.1% of first MOT tests, 36% fewer MOT fails than the average car its age and mileage, based on 8,444 DVSA MOT tests from 2022 to 2024.
Checking a Mercedes-Benz GLS before you buy?
- first-time MOT fail rate (all cars: 28.4%)
- 11.1%
- first-time MOT fail rate (all cars: 28.4%)
- fails than cars of the same age and mileage
- 36% fewer
- fails than cars of the same age and mileage
- MOT tests analysed, 2022 to 2024
- 8,444
- MOT tests analysed, 2022 to 2024
- typical miles a year, from MOT readings
- 9,700
- typical miles a year, from MOT readings
MOT fail rate by age
How the Mercedes-Benz GLS ages
Each point is the share of Mercedes-Benz GLSs of that age that failed their MOT first time, against all cars of the same age.
| Age at MOT (years) | Mercedes-Benz GLS | All cars |
|---|---|---|
| 3 | 9.9% | 12.3% |
| 4 | 9.2% | 14.1% |
| 5 | 13.5% | 16.4% |
| 6 | 12.1% | 19.1% |
| 7 | 8.1% | 22.1% |
| 8 | 20.7% | 25.5% |
By year
The best and worst Mercedes-Benz GLS years
2019 cars come out best and 2020 cars worst, once age and mileage are taken into account.
| First registered | Tests | Fail rate | Against same-age cars | Typical mileage |
|---|---|---|---|---|
| 2021 | 264 | 4.5% | 65% fewer fails | 31,100 |
| 2020 GLS | 1,109 | 10.6% | 25% fewer fails | 38,079 |
| 2019 GLS | 1,255 | 8% | 45% fewer fails | 39,014 |
| 2018 GLS | 2,044 | 11.9% | 26% fewer fails | 42,918 |
| 2017 GLS | 2,259 | 11.2% | 40% fewer fails | 51,996 |
| 2016 GLS | 1,510 | 14.1% | 36% fewer fails | 62,047 |
Common problems
What fails most on a Mercedes-Benz GLS
Its weak spot is tyres: 13% more fails there than cars of the same age and mileage.
Fail rate by area
- Tyres6.3%13% above avg
- Brakes1.5%55% below avg
- Lights and electrics1%78% below avg
- Exhaust, emissions and leaks0.9%23% below avg
- Number plates and VIN0.8%223% above avg
- Windscreen, wipers and mirrors0.7%78% below avg
- Body, chassis and structure0.7%15% below avg
- Suspension0.4%84% below avg
- Seat belts and airbags0.3%16% below avg
Average for cars of the same age and mileage
Top MOT failures
- 1
Tyre tread below 1.6mm 1.88% of tests
Tread below 1.6mm is illegal and reduces grip in wet conditions, so the tyre must be replaced.
- 2
Tyre cut reaching ply or cords 1.53% of tests
A cut reaching the ply or cords weakens the tyre and can cause a burst, so it must be replaced.
- 3
Tyre ply or cords exposed 1.37% of tests
Exposed ply or cords can let the tyre fail suddenly, so the tyre must be replaced before the car is driven.
- 4
Brake pads worn below 1.5mm 0.53% of tests
Pads worn below 1.5mm lose stopping power and can damage discs, so replacement is needed before the car is driven.
- 5
Number plate does not meet standards 0.52% of tests
The plate does not meet legal specifications, so it must be replaced with a compliant one before the car is driven.
- 6
Brake pads worn to wear indicator 0.5% of tests
Pads worn to the indicator are at their limit, reducing braking and needing immediate replacement.
- 7
Tyre bulge from structural failure 0.49% of tests
A bulge means the tyre's structure has failed and it could burst suddenly, so it must be replaced at once.
- 8
CV joint boot split or insecure 0.37% of tests
A split CV boot lets dirt in and grease out, so the joint wears and may need full replacement.
Most common advisories
Not a fail yet, but worth pricing in: these show up on a Mercedes-Benz GLS's MOT certificate most often.
- Tyre worn close to legal limit9.36%
- Brake pads wearing thin4.49%
- Brake disc pitted or scored2.13%
- Child seat limits belt inspection1.87%
- Brake discs showing some wear1.86%
- Tyre worn close to legal limit1.73%
Before you buy
What to check on a used Mercedes-Benz GLS
- 1
Tyre tread below 1.6mm
Tread below 1.6mm is illegal and reduces grip in wet conditions, so the tyre must be replaced.
- 2
Tyre cut reaching ply or cords
A cut reaching the ply or cords weakens the tyre and can cause a burst, so it must be replaced.
- 3
Tyre ply or cords exposed
Exposed ply or cords can let the tyre fail suddenly, so the tyre must be replaced before the car is driven.
- 4
Brake pads worn below 1.5mm
Pads worn below 1.5mm lose stopping power and can damage discs, so replacement is needed before the car is driven.
- 5
Every MOT since new
Look for the faults above coming back year after year: it shows how the car has been looked after.
- 6
The mileage record
A typical Mercedes-Benz GLS covers about 9,700 miles a year. A big gap or a drop between MOTs is a warning sign.
- 7
Finance, stolen and write-off
The records the MOT can't show. A Full Check (£9.99) covers all three before you hand over any money.
Fuel types tested
- Diesel87.8%
- Petrol12.1%
- Hybrid0.1%
Most common colours
Black, Grey, White, Silver, Blue
Average engine size: 3.3 litres.
Compare
How the Mercedes-Benz GLS compares with its rivals
| Model | Fail rate | Against same-age cars |
|---|---|---|
| Mercedes-Benz GL-Class | 17.8% | 46% fewer MOT fails than the average car its age |
| Mercedes-Benz G-Class | 13.7% | 39% fewer MOT fails than the average car its age |
| Mercedes-Benz GLS | 11.1% | 36% fewer MOT fails than the average car its age |
| Mercedes-Benz R-Class | 27.2% | 34% fewer MOT fails than the average car its age |
| Mitsubishi Pajero | 32.5% | 24% fewer MOT fails than the average car its age |
| Nissan Terrano | 45.1% | 4% more MOT fails than the average car its age |
| SsangYong Rexton | 35.6% | 36% more MOT fails than the average car its age |
Every large suv ranked in the large suv reliability index, or all Mercedes-Benz models.
Questions
Mercedes-Benz GLS questions, answered
Is the Mercedes-Benz GLS reliable?
On MOT results, the Mercedes-Benz GLS is better than average: it fails 11.1% of first MOT tests, 36% fewer MOT fails than the average car its age and mileage. It ranks 13 of 30 large suv models in our index.
What fails most on a Mercedes-Benz GLS MOT?
The most common MOT failures on the Mercedes-Benz GLS are tyre tread below 1.6mm (1.88% of tests), tyre cut reaching ply or cords (1.53% of tests), tyre ply or cords exposed (1.37% of tests). By area, tyres fails 6.3% of its tests.
Which Mercedes-Benz GLS year is the most reliable?
Among years with 1,000+ tests, 2019 cars do best (45% fewer MOT fails than the average car its age) and 2020 cars do worst (25% fewer MOT fails than the average car its age).
How many miles does a Mercedes-Benz GLS do a year?
A typical Mercedes-Benz GLS covers about 9,700 miles a year, from the mileage recorded at its MOTs. Check the car you're looking at against that with a free mileage check.
How do I check a Mercedes-Benz GLS before I buy it?
Enter its registration for a free check of its MOT history, mileage, ULEZ status and tax. Before you pay, a Full Check (£9.99) shows outstanding finance, stolen and write-off records.
Source: DVSA anonymised MOT test results, 2022 to 2024, class 4 vehicles aged 3 to 25, normal tests only. How we compare like with like: our methodology.
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