Used car guide

2021 Mercedes-Benz A: common problems and what to check

What gets flagged at MOT on 2021 Mercedes-Benz As, from 29,555 tests in 2025, plus known faults and what to look at before you buy one.

29,555MOT tests in 2025
90%pass first time (all 2021 cars: 87%)
8,300typical miles a year
26%had tyres flagged

What gets flagged at MOT

The share of 2021 Mercedes-Benz A MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

  • Tyres
    26% 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
    10% 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.

  • Wipers, windscreen and mirrors
    5% of testsRough price £15–£250

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

  • 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.

  • Seats and seatbelts
    2% of testsRough price £80–£250

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

  • Lights and electrics
    2% of testsRough price £10–£80

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

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Other years

YearMOT testsMost flagged
2023734Tyres 13%
202217,786Tyres 24%
202035,472Tyres 29%
201942,686Tyres 30%
2018925Tyres 32%
2014509Tyres 33%
20131,170Tyres 35%

Where this comes from: the DVSA's anonymised results for every MOT test in Great Britain in 2025, counting tests of 2021 Mercedes-Benz As registered in 2021. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score