Mercedes Benz
18,726 MOT tests analysed. sits above the UK fleet average — here's where Slcs pass, fail, and end up on the retest sheet.
That's 11.6 points above the UK fleet average across our 1,984 tracked models — a confident result.
Pass
89.1%
Pass-after-fix
1.5%
Fail
9.1%
Avg miles
34,481
Pass + Pass-after-fix + Fail = 100%
This model's production run straddles the January 2006 Euro 4 cutoff. Individual cars vary — check your registration plate on the government's ULEZ checker. Daily charges if driven in the zone: London £12.50 · Birmingham £8.00 .
Performance by cohort
2 year bands · 18,639 tests
Pass rate climbs 3.8 points across the cohorts — newer Slc examples clear the test more reliably than the early cars.
Pass
88.4%
Fail
9.8%
PRS
1.6%
Avg mileage at test
37,189 mi
Pass
92.1%
Fail
6.6%
PRS
1.1%
Avg mileage at test
23,967 mi
Cohort = vehicle's first-registration year band. Same model, different generations of build.
The picture
Across 9,233 MOT tests, the Slc returns 88.1% first-time pass — comfortably ahead of the UK fleet average. The single most-logged Major fail is a tyre with the cords showing. A seriously damaged tyre and tyre tread under the limit round out the top three. Average tested mileage sits at 29,787, 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 →
36–46
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A tyre cords visible or damaged
337 occurrences · 1.8% of tests
A tyre seriously damaged
226 occurrences · 1.2% of tests
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
190 occurrences · 1.0% of tests
Tyre tread depth not in accordance with the requirements
169 occurrences · 0.9% of tests
A spring or spring component fractured or seriously weakened
159 occurrences · 0.8% of tests
A suspension pin, bush or joint excessively worn
132 occurrences · 0.7% of tests
A suspension joint dust cover severely deteriorated
130 occurrences · 0.7% of tests
A suspension joint dust cover missing or no longer prevents the ingress of dirt etc
79 occurrences · 0.4% of tests
A tyre seriously damaged
75 occurrences · 0.4% of tests
Warning device shows system malfunction
72 occurrences · 0.4% 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
£200–£430
If every one of this Slc'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.
Year-band analysis
First-time MOT pass rate split by registration band. A 3.8-point gap between bands means the year you buy Mercedes Benz Slc has a real effect on what turns up at the garage.
Best band to buy
92.1%
2018–2020 registration
the 2018–2020 band climbs to 92.1% — a 3.8-point improvement. Tests in this band average 23,967 miles — roughly 13K miles fewer on the clock than the older band. Failures here are mostly wear items: has ply or cords exposed, 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. The stricter post-2018 MOT test rules meant manufacturers had to tighten up emissions and electrical checks, but this band still shows far fewer major failures on suspension and bodywork than the older fleet.
Band to be cautious about
88.4%
Pre-2018 registration
On the older band (pre-2018), the data shows a 88.4% pass rate against a fleet average of 92.1% on the newer band. The main culprits logged at test: has ply or cords exposed, has a cut in excess of the…, and tread depth below requirements of 1.6mm. Average mileage on test for this band is 37,189 miles — high-mileage wear items are a recurring theme.
Best band to buy: 2018-2020 (92.1% first-time pass). Worst band to avoid: pre-2018 (88.4% pass). That's a 3.8-point spread across 14,959 older tests and 3,680 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.
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Mobile mechanic · UK-wide
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Owner reports · Honest John
Verbatim faults logged by owners on honestjohn.co.uk over recent years. We didn't summarise — these are the words people typed in.
Where it falls short
Boot space is heavily compromised by lowering the roof, ride quality is harsh on all models, and worse with AMG suspension, dated dashboard betrays the age of the car underneath.
Recall history
The Slc has 4 official UK vehicle recalls covering defect details, remedies, and affected build dates.
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 Slc 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.
