Mercedes Benz
2,027 MOT tests analysed. sits above the UK fleet average — here's where Glc 300 Amg Line Prem + 4M As pass, fail, and end up on the retest sheet.
That's 15.3 points above the UK fleet average across our 1,984 tracked models — a confident result.
Pass
92.8%
Pass-after-fix
1.7%
Fail
5.3%
Avg miles
27,849
Pass + Pass-after-fix + Fail = 100%
Petrol cars first registered from January 2006 meet Euro 4 — compliant in London ULEZ, Birmingham CAZ, Bristol CAZ, and Glasgow LEZ.
Performance by cohort
2 year bands · 2,027 tests
Pass rate is broadly flat across the cohorts — new and old Glc 300 Amg Line Prem + 4M A examples track each other at the test bay.
Pass
92.7%
Fail
5.3%
PRS
1.8%
Avg mileage at test
29,272 mi
Pass
93.0%
Fail
5.2%
PRS
1.3%
Avg mileage at test
24,050 mi
Cohort = vehicle's first-registration year band. Same model, different generations of build.
The picture
Across 885 MOT tests, the Glc 300 Amg Line Prem + 4m A returns 91.5% 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 22,791, 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.
ABI Insurance Group
A high-group car — insurance costs will be significantly above average. Lower groups cost less to insure; UK fleet average is around Group 22.
Source: ABI Group Rating Panel · administered by Thatcham Research · groups cover standard variants; performance trims may sit higher. Browse all insurance groups →
32–44
out of 50
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A tyre seriously damaged
40 occurrences · 2.0% of tests
A tyre cords visible or damaged
23 occurrences · 1.1% of tests
Wiper blade defective
23 occurrences · 1.1% of tests
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
20 occurrences · 1.0% of tests
A suspension pin, bush or joint excessively worn
7 occurrences · 0.3% of tests
Brake lining or pad worn down to wear indicator
7 occurrences · 0.3% of tests
Number plate does not conform to the specified requirements
7 occurrences · 0.3% of tests
a brake lining or pad worn below 1.5mm
6 occurrences · 0.3% of tests
Tyre tread depth not in accordance with the requirements
6 occurrences · 0.3% of tests
Engine MIL illuminated indicating a malfunction
5 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
£160–£380
If every one of this Glc 300 Amg Line Prem + 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 + 4M A makes little measurable difference to MOT outcomes.
Best band to buy
93.0%
2021+ registration
the 2021-on band climbs to 93.0% — a 0.3-point improvement. Tests in this band average 24,050 miles — roughly 5K miles fewer on the clock than the older band. Failures here are mostly wear items: blade defective, has a cut in excess of the… — the structural issues that drag down older examples don't appear in the top-10 for this band. Post-2020 examples are early in their MOT life and generally show the cleanest records.
Band to be cautious about
92.7%
2018–2020 registration
On the 2018–2020 band, the data shows a 92.7% pass rate against a fleet average of 93.0% on the newer band. The main culprits logged at test: has a cut in excess of the…, has ply or cords exposed, and blade defective. Average mileage on test for this band is 29,272 miles — high-mileage wear items are a recurring theme.
Best band to buy: 2021+ (93.0% first-time pass). Worst band to avoid: 2018-2020 (92.7% pass). That's a 0.3-point spread across 1,471 older tests and 556 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
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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 + 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.
