Used car guide

2018 Mercedes-Benz GLS: common problems and what to check

What gets flagged at MOT on 2018 Mercedes-Benz GLSs, from 556 tests in 2025, plus known faults and what to look at before you buy one.

556MOT tests in 2025
86%pass first time (all 2018 cars: 81%)
8,700typical miles a year
5.7×the usual rate for drive shaft (cv) joints

What stands out

Parts flagged at MOT more often on 2018 Mercedes-Benz GLSs than on all cars registered in 2018.

  • Drive shaft (CV) joints5.7× usual
    Mercedes-Benz GLS
    6.3% All 2018 cars
    1.1%

    Failed outright at MOT: 1.3%, against 0.6% of all 2018 cars. The rest were advisories or minor defects.

    Rough price £60–£350 our estimate

    At the viewing: Drive slowly on full steering lock in both directions and listen for clicking. Look for split rubber boots behind the front wheels.

By area

The share of 2018 Mercedes-Benz GLS MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

  • Tyres
    27% 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
    13% 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.

  • Driveshafts and joints
    6% of testsRough price £60–£350

    At the viewing: On full steering lock, drive slowly and listen for clicking from the front wheels.

  • Wipers, windscreen and mirrors
    4% of testsRough price £15–£250

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

  • 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.

  • Suspension
    2% 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.

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Other years

YearMOT testsMost flagged
2017605Tyres 30%

Where this comes from: the DVSA's anonymised results for every MOT test in Great Britain in 2025, counting tests of 2018 Mercedes-Benz GLSs registered in 2018. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score