Used car guide

2020 Mercedes-Benz GLS: common problems and MOT failures

What MOT testers find on the Mercedes-Benz GLS first registered in 2020: we looked at the 1,189 MOTs these cars had during 2023–2025. Plus known faults and what to look at before you buy one.

1,189MOTs of 2020 cars, done in 2023–2025
86%pass first time (all 2020 cars: 87%)
9,600typical miles a year
6.3×the usual rate for ball joint

What goes wrong more than usual on a 2020 Mercedes-Benz GLS?

Parts flagged at MOT more often on the 2020 Mercedes-Benz GLS than on all cars registered in 2020.

  • Ball joint6.3× usual
    Mercedes-Benz GLS
    2.5% All 2020 cars
    0.4%

    Failed outright at MOT: 0.8%, against 0.1% of all 2020 cars. The rest were advisories or minor defects.

    Rough price £60–£150 (one joint) ClickMechanic

    At the viewing: Listen for knocking over bumps and check the rubber boots behind the wheels aren't split.

Better than most

Brake discs: 2.5% here, against 7.4% of all 2020 cars.

Common 2020 Mercedes-Benz GLS MOT failures and advisories

The share of 2020 Mercedes-Benz GLS MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

  • Tyres
    24% of testsRough price £70–£150

    At the viewing: Check the tread on all four tyres, including the inside edges, and look for cracks or bulges.

  • Brakes
    9% of testsRough price £150–£350

    At the viewing: Look for a lip on the disc edges and feel for judder or pulling when braking firmly from about 40mph.

  • Suspension
    5% of testsRough price £120–£400

    At the viewing: Listen for knocks over speed bumps, and look behind each front wheel for a snapped coil spring.

  • Seats and seatbelts
    3% of testsRough price £80–£250

    At the viewing: Pull each seatbelt sharply. It should lock, and retract cleanly.

  • Lights and electrics
    3% of testsRough price £10–£80

    At the viewing: Ask a friend to check every light, including brake lights and indicators, while you operate them.

  • Wipers, windscreen and mirrors
    3% of testsRough price £15–£250

    At the viewing: Check for chips in the driver's view, and test the wipers and washers.

Questions to ask the seller before buying a 2020 Mercedes-Benz GLS

Ask before you travel to see it. A seller who knows the car will have answers, and receipts.

  1. Any recent work on the ball joint? (Flagged at MOT 6.3× as often on the 2020 Mercedes-Benz GLS as on other cars the same age.)
  2. Can I see the service history and receipts for any big jobs?

Looking at a Mercedes-Benz GLS?

Check the actual car: its own MOT history, mileage and what to ask the seller. Free, no sign-up.

Other years

Every year of the Mercedes-Benz GLS compared

YearMOT testsMost flagged
2026–Too new for MOT data
2025–Too new for MOT data
2024–Too new for MOT data
2023–Too new for MOT data
2022358Tyres 26%
2021537Tyres 26%
20191,158Tyres 23%
20181,706Tyres 25%
20171,879Tyres 26%
20161,195Tyres 25%

Where this comes from: the DVSA's anonymised results for every MOT test done in Great Britain during 2023–2025, counting the MOTs of Mercedes-Benz GLS cars first registered in 2020. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score