MOT cost .

Mercedes Benz

GL 320

542 MOT tests analysed. lands in the middle of the pack — here's where GL 320 s pass, fail, and end up on the retest sheet.

That's 0.8 points below the UK fleet average across our 1,988 tracked models — buyers should expect more first-time fails than the typical UK car.

Pass

74.9%

Pass-after-fix

5.7%

Fail

18.3%

Avg miles

127,459

Pass + Pass-after-fix + Fail = 100%

The picture

Gl 320 : middle-of-the-pack on first-time pass

Across 542 MOT tests, the Gl 320 returns 74.9% first-time pass — below the UK fleet average. The single most-logged Major fail is a split CV-joint boot. A number-plate lamp out and a corroded brake pipe round out the top three. Average tested mileage sits at 127,459, which is the lens to read those failure rankings through. If you own one and the next test is close, the ranked list below is a sensible pre-test checklist.

Top ten reasons for rejection.

  1. 01

    A transmission shaft constant velocity joint boot severely deteriorated

    38 occurrences · 7.0% of tests

  2. 02

    A rear registration plate lamp or light source missing or inoperative in the case of multiple lamps or light sources

    26 occurrences · 4.8% of tests

  3. 03

    Brake pipe damaged or excessively corroded

    21 occurrences · 3.9% of tests

  4. 04

    Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view

    19 occurrences · 3.5% of tests

  5. 05

    Tyre tread depth not in accordance with the requirements

    19 occurrences · 3.5% of tests

  6. 06

    A lamp missing, inoperative or in the case of a multiple light source more than 1/2 not functioning

    14 occurrences · 2.6% of tests

  7. 07

    Reflector defective or damaged by up to 50% of the reflecting surface

    12 occurrences · 2.2% of tests

  8. 08

    A wheel with a loose or missing wheel nut, bolt or stud

    11 occurrences · 2.0% of tests

  9. 09

    A shock absorber damaged to the extent that it does not function or showing signs of severe leakage

    11 occurrences · 2.0% of tests

  10. 10

    Number plate does not conform to the specified requirements

    9 occurrences · 1.7% of tests

Counts cover Major and Dangerous defects logged at test. Advisory items excluded so this shows why a car was rejected, not just what the tester flagged in passing.

Worst-case fix budget · top 3 failures

£108–£220

If every one of this GL 320 's most-logged Major fails hit at the same MOT, that's the real-world UK garage range. Reality is usually one or two items, not all of them. Open the estimator →

Try the calculator

Build your own retest budget.

Tools that pre-empt a retest.

Picked against this car's top failure patterns. Affiliate links to Amazon UK — we earn a small cut at no cost to you. Disclosed up-front, doesn't shape the data.

Item 01 · Amazon UK

H7 / W21W bulb pack

A spare-bulb kit lives in the boot. Test morning is not the time to find your stop-lamp's gone.

Search Amazon UK

Item 02 · Amazon UK

Digital tyre-tread depth gauge

Five quid for a gauge beats £150 for a retest. UK MOT minimum is 1.6mm — most testers fail anything below 2mm to be safe.

Search Amazon UK

Buying or keeping a GL 320 ?

Use the failure ranking as a pre-test checklist or a haggling lever. Treat the headline pass rate as a fleet-wide trend, not a guarantee on any individual car.

If you own a GL 320 and your last MOT looked nothing like the ranked failures above, that's normal — individual cars vary widely. The ranking shows the patterns testers flag most often across the country.