Used car guide

2018 MG 3: common problems and what to check

What gets flagged at MOT on 2018 MG 3s, from 2,550 tests in 2025, plus known faults and what to look at before you buy one.

2,550MOT tests in 2025
72%pass first time (all 2018 cars: 81%)
5,600typical miles a year
71×the usual rate for suspension arm

What stands out

Parts flagged at MOT more often on 2018 MG 3s than on all cars registered in 2018.

  • Suspension arm71× usual
    MG 3
    7.1% All 2018 cars
    0.1%

    Failed outright at MOT: 0%, against 0% of all 2018 cars. The rest were advisories or minor defects.

    Rough price £120–£180 (one arm) ClickMechanic

    At the viewing: Listen for clunks over bumps and feel for the steering wandering. Worn arm bushes show as cracked rubber near the wheels.

  • Sub-frame34× usual
    MG 3
    6.8% All 2018 cars
    0.2%

    Failed outright at MOT: 0.2%, against 0% of all 2018 cars. The rest were advisories or minor defects.

    Rough price £300–£1,000 our estimate

    At the viewing: Look underneath at the frame the suspension bolts to. Flaky rust or holes are expensive to fix.

  • Coil springs3.8× usual
    MG 3
    6.4% All 2018 cars
    1.7%

    Failed outright at MOT: 3.3%, against 1.3% of all 2018 cars. The rest were advisories or minor defects.

    Rough price £175–£400 (pair, one axle) ClickMechanic

    At the viewing: Look behind each wheel for a snapped spring coil, and listen for a clunk or twang when turning the wheel lock to lock with the car stopped.

  • Rigid brake pipes6.6× usual
    MG 3
    5.3% All 2018 cars
    0.8%

    Failed outright at MOT: 0.7%, against 0.1% of all 2018 cars. The rest were advisories or minor defects.

    Rough price £100–£400 our estimate

    At the viewing: Ask to see underneath, or check the MOT advisories: corroded brake or fuel pipes get worse every year and fail the MOT when they do.

  • Wipers2.7× usual
    MG 3
    6.7% All 2018 cars
    2.5%

    Failed outright at MOT: 4.3%, against 1.5% of all 2018 cars. The rest were advisories or minor defects.

    Rough price £15–£60 our estimate

    At the viewing: Test the wipers and washers on every speed.

By area

The share of 2018 MG 3 MOT tests where testers flagged each area, as a fail or an advisory. Rough prices are typical independent-garage costs.

  • Tyres
    34% 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
    28% 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
    21% 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.

  • Lights and electrics
    12% 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
    10% of testsRough price £15–£250

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

  • Oil and fluid leaks
    3% of testsRough price £80–£600

    At the viewing: Look under the engine and on the ground where the car is usually parked for fresh oil or fluid.

Looking at a MG 3?

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Other years

YearMOT testsMost flagged
20224,274Tyres 26%
20211,929Tyres 32%
20202,471Tyres 34%
20193,635Tyres 34%
20172,844Tyres 36%
20163,065Suspension 37%
20152,269Suspension 39%
20141,524Suspension 39%

Where this comes from: the DVSA's anonymised results for every MOT test in Great Britain in 2025, counting tests of 2018 MG 3s registered in 2018. "Flagged" includes advisories, so it isn't the same as a fail rate. How we score