Photo: Alexander Migl, CC BY-SA 4.0
Mercedes Benz
1,911 MOT tests analysed. sits above the UK fleet average — here's where Glc 300 Amg Line Prem DE 4M As pass, fail, and end up on the retest sheet.
That's 16.4 points above the UK fleet average across our 1,984 tracked models — a confident result.
Pass
93.9%
Pass-after-fix
0.5%
Fail
5.7%
Avg miles
35,594
Pass + Pass-after-fix + Fail = 100%
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Performance by cohort
2 year bands · 1,911 tests
Pass rate is broadly flat across the cohorts — new and old Glc 300 Amg Line Prem DE 4M A examples track each other at the test bay.
Pass
94.2%
Fail
5.3%
PRS
0.5%
Avg mileage at test
39,366 mi
Pass
93.7%
Fail
5.8%
PRS
0.5%
Avg mileage at test
33,765 mi
Cohort = vehicle's first-registration year band. Same model, different generations of build.
The picture
Across 1,911 MOT tests, the Glc 300 Amg Line Prem De 4m A returns 93.9% first-time pass — comfortably ahead of the UK fleet average. The single most-logged Major fail is a seriously damaged tyre. A tyre with the cords showing and windscreen damage round out the top three. Average tested mileage sits at 35,594, 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.
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A tyre seriously damaged
42 occurrences · 2.2% of tests
A tyre cords visible or damaged
36 occurrences · 1.9% of tests
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
30 occurrences · 1.6% of tests
Wiper blade defective
18 occurrences · 0.9% of tests
Tyre tread depth not in accordance with the requirements
15 occurrences · 0.8% of tests
Number plate does not conform to the specified requirements
4 occurrences · 0.2% of tests
Windscreen washers not working or not providing sufficient fluid to clear the windscreen
3 occurrences · 0.2% of tests
Engine MIL illuminated indicating a malfunction
3 occurrences · 0.2% of tests
A transmission shaft constant velocity joint boot severely deteriorated
3 occurrences · 0.2% of tests
A tyre cords visible or damaged
3 occurrences · 0.2% 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
£140–£235
If every one of this Glc 300 Amg Line Prem DE 4M A'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 →
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Build your own retest budget.
Year-band analysis
First-time MOT pass rate split by registration band. Pass rates barely move across bands here, so the year you buy Mercedes Benz Glc 300 Amg Line Prem DE 4M A makes little measurable difference to MOT outcomes.
Best band to buy
94.2%
2018–2020 registration
the 2018–2020 band climbs to 94.2% — a 0.5-point improvement. Failures here are mostly wear items: has a cut in excess of the…, damaged but not adversely affecting driver's view — the structural issues that drag down older examples don't appear in the top-10 for this band.
Band to be cautious about
93.7%
2021+ registration
On the 2021-on band, the data shows a 93.7% pass rate against a fleet average of 94.2% on the newer band. The main culprits logged at test: has ply or cords exposed, has a cut in excess of the…, and damaged but not adversely affecting driver's view. Average mileage on test for this band is 33,765 miles — high-mileage wear items are a recurring theme.
Best band to buy: 2018-2020 (94.2% first-time pass). Worst band to avoid: 2021+ (93.7% pass). That's a 0.5-point spread across 1,287 older tests and 624 newer ones — year of build makes a material difference on this model.
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
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
Item 02 · Amazon UK
Bosch Aerotwin wiper blades
Cheap wipers fail the test on smear streaks. Bosch Aerotwins last a winter and clear a screen properly.
Search Amazon UK
My Motor World · affiliate
Affiliate links — small commission, no extra cost to you.
Click Mechanic · affiliate
Affiliate links — small commission, no extra cost to you.
Mobile mechanic · UK-wide
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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 Glc 300 Amg Line Prem DE 4M A 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.
