Mercedes-Benz SLC — MOT statistics 2024

The Mercedes-Benz SLC failed 13.71% of 8,972 first MOT attempts in 2024 ("first-time", excluding retests). Adjusted for the age of the fleet, its initial-failure ratio is 70.9 (100 = expected for its age profile). This car fails its MOT about 29% less often than expected for its age.

Age-adjusted peer: Land Rover Range Rover (index 70.9) — the two published results are 0.0 index points apart.

Mercedes-Benz SLC common problems: what actually fails the MOT

Lamps, reflectors and electrical equipment are well below the reference at 1.0 per 100 tests, against 4.2 per 100 tests across UK vehicles of the same ages.

higher bar = fails more oftenrate per 100 tests

family vs national — matched to UK vehicles of the same ages — top component groups, per 100 tests. Legend: This family · National avg. Combined labels: family / national average. A gap here reflects how these vehicles are driven, used and maintained as well as how they were built — an MOT defect is a test outcome, not a breakdown.

Named defects ranked by how much more often they appear than the national average — not by raw rate.

Mercedes-Benz SLC MOT advisories: what gets flagged

Tyres are highest at 40.2 per 100 tests; Identification is lowest at 0.4 per 100 tests — the gap is 39.8 per 100 tests.

higher bar = flagged more oftenadvisory items per 100 initial tests

Advisories are wear the tester noted but didn't fail — what will need money soon.

Tyres, brakes and suspension: Mercedes-Benz SLC against cars of the same age

Failing items per 100 initial tests, 2019-2024. The comparison group is every petrol or diesel car tested at the same age, so weight and drivetrain show up rather than fleet age.

If a car like this fails, does it fail again?

A failure rate does not say whether a failure is a one-off or the start of something. This follows the same vehicles into their next ordinary MOT a year later — retests after a repair are excluded, because they follow a failure by definition. 2019-2024.

A failed test raises next year's chance of failing again by 3.2 percentage points. The failure most likely to come back is tyres — 22.2% of those vehicles fail again next year. Some of this is the vehicle and some is the owner: a car that was let go once tends to be let go again. One caveat: a car that fails may be sold or scrapped rather than tested again, so these figures describe the vehicles that came back.

Adjusted for how much these are actually driven

The headline index adjusts for the fleet's age. Wear, though, follows mileage: a three-year-old taxi and a three-year-old garage queen sit in the same age band. These two rows compare every car with vehicles of the same age, and then with vehicles of the same age and the same annual mileage, 2019-2024, on 41,494 tests. Both stand on the six-year corpus so they are measured on identical data — compare them with each other, not with the headline index above, which is measured on 2024 alone.

Mileage matters here: matching on how much these are driven moves the figure by 18.9 points — this fleet is driven less than the vehicles it is measured against, so the age-only view flatters it — but it does not change which side of normal the car sits on. One limit to keep in mind: mileage is partly a result of how often a car breaks down — one that spends weeks in the workshop covers fewer miles — so the mileage-matched figure can understate a real weakness. Tests with no usable odometer reading are left out of it.

How the Mercedes-Benz SLC compares with cars of its own age and size

Not against the whole fleet — against cars of the same size class tested at the same age, 2019-2024.

Raw first-time failure rates within each age, so fleet age cannot flatter either side. A positive difference means this model fails more often than its own class at that age.

How does the Mercedes-Benz SLC perform as it gets older?

The SLC at age 8 is well below the reference at 16.5%, against 23.3% for all vehicles of the same age.

higher = larger sharecompare shares in percentage points

Chart axes: car age, years · failure-rate scale 0–29%.

Takeaway: solid line: this family; dashed: all cars.

Mercedes-Benz SLC petrol vs diesel: which ages best

Diesel is highest at 18.5%; Petrol is lowest at 11.5% — the gap is 7.0 percentage points.

higher = larger sharecompare shares in percentage points

Chart sample sizes: n=6,139 · n=2,833.

How dangerous are Mercedes-Benz SLC MOT failures?

Major defects are well below the reference at 8.2 per 100 tests, against 52.8 per 100 tests nationally.

higher bar = fails more oftenrate per 100 tests

Chart values: Minor 2.7 · Major 8.2 · Dangerous 6.9.

Per 100 tests on this family. National average: Minor 14.2 · Major 52.8 · Dangerous 11.2 per 100.

Does the month of a Mercedes-Benz SLC MOT matter?

Nov is highest at 12.6%; Mar is lowest at 10.1% — the gap is 2.5 percentage points.

higher = larger sharecompare shares in percentage points

Chart scale: 9%–33%.

bars: Mercedes-Benz SLC · dashed: all class-4 cars

Takeaway: the spread between best and worst month is 2.5 percentage points — booking month barely matters for this family. Seasonality partly reflects registration-date clustering, not weather.

Before reading the shape: most of it is not about cars. Britain changes its registration plates twice a year, and 18.9% of these cars were first registered in March with another17.1% in September — 36% in two months against the 17% an even spread would give. An MOT falls due three years after first registration, so the buying calendar becomes the testing calendar. That shapes how many cars are tested each month — not how often they fail: the busiest months here are not the worst ones, so read the failure line on its own and the volume behind it separately.

Mercedes-Benz SLC average mileage by age

At age 8, the middle half of SLCs runs from 26,186 miles to 51,377 miles, against 37,346 miles as the median.

further right = more milesmedian is the typical car; band is p25–p75

Chart axes: car age, years · odometer scale 0–54k mi.

Does high mileage mean more Mercedes-Benz SLC MOT failures at the same age?

Within the same age group, split by odometer (2024 MOTs), so this separates wear from age: at ages 6–9, 11.7% of those with under 40,000 miles failed first time versus 23.1% of those with 70,000–100,000 miles.Inside this age group, higher mileage goes with more failures.

line: median · band: middle half of the fleet (p25–p75)

A typical 8-year-old SLC has ~37,346 miles on the clock. Much more — ask why; much less — check for gaps in the MOT history.

Where in Britain the Mercedes-Benz SLC fails its MOT most

Watford area is highest at 21.0%; Nottingham area is lowest at 4.4% — the gap is 16.7 percentage points.

higher = larger sharecompare shares in percentage points

Toughest areas	% failing	vs model overall
Watford (WD)	21.03%	+9.5 pp
Bradford (BD)	17.13%	+5.6 pp
Kilmarnock (KA)	16.35%	+4.8 pp
Darlington (DL)	16.3%	+4.8 pp
Canterbury (CT)	15.85%	+4.3 pp

Easiest areas	% failing	vs model overall
Nottingham (NG)	4.35%	-7.2 pp
Harrow (HA)	6.32%	-5.2 pp
London NW (NW)	6.67%	-4.8 pp
Kingston upon Thames (KT)	8.45%	-3.1 pp

Every dot is a postcode area — size = how many were tested there, colour = share failing. These figures are not age-adjusted: coastal and rural areas often run older fleets and salted roads, so higher raw fail rates do not automatically mean a worse local stock of this model.

Map labels: Scotland · N. England · Wales · London · S. West. Colour scale: 8%–16% failing.

Mercedes-Benz SLC survival: which cars are still on the road

By age 8 is well below the reference at 27.8%, against 100.0% at the ages 4–6 reference level.

higher = larger sharecompare shares in percentage points

Chart axes: car age, years · survival vs ages 4–6 · scale 0–105%.

By age 8, only about 28% as many cars of this family present for MOT as at ages 4–6 (reference n≈8,116); survivors still fail at 16.6% vs 9.8% at age 4. Older cars that still appear are a selected subset — weaker ones have already left.

How many years is a Mercedes-Benz SLC likely to last?

Bought at age 5 is highest at 2.4 years; Bought at age 8 is lowest at 0.5 years — the gap is 1.9 years.

bigger number = longer remaining lifeyears on the observed survival curve

estimateObserved only until age 8. The curve does not run five years past the stated age with the share still tested under 50%, so no 'years left' number is given.

Mercedes-Benz SLC faults that come together

Brakes + Emissions & leaks stand out at 15.38×, against 1.00× if the faults were independent.

above 1.0× = more than expectedbelow 1.0× = less

Defects in «Brakes» and «Noise, emissions and leaks» appear together 15.38× more often than chance (41 co-occurrences in the same test; 55 pairs compared).

Lift = how many times more often both groups appear on the same test than if independent. A pair is listed from 5 tests with both faults; the lift is shown from 20, and called above chance only when its 95% interval excludes 1 (see rough estimates).

Is low mileage better for a Mercedes-Benz SLC?

Cars driven under 5,000 miles a year is well below the reference at 9.3%, against 19.3% for cars driven 8,000–12,000 miles a year.

higher = larger sharecompare shares in percentage points

At matched ages 5–14, cars averaging under 5k miles/year fail at 9.3% vs 19.2% for 8–12k miles/year — 9.9 pp lower (n_low=11,865, n_normal=2,275). In this family low annual use is associated with fewer MOT fails, not more — the ‘garage queen’ penalty is not visible in overall fail rates.

Which Mercedes-Benz SLC engine is best?

diesel over 2.0 is highest at 120.6; petrol 1.5–1.8 is lowest at 85.5 — the gap is 35.1 points.

below 100 is betterabove 100 is worse100 = normal for this model at that age

Splitting this model by fuel alone hides the thing that actually differs. Within the same badge, the diesel over 2.0 runs at 120.6 against this model's own age norm while the petrol 1.8–2.0 runs at 86 — a spread of 34.6 points between two cars that share a name.

Read this one with more care than the rest of the page. Age is held constant, but who buys which engine is not: the largest capacity in a range is often a performance or executive variant that is garaged, cherished and lightly driven, while the smallest is frequently a fleet or entry car worked hard from new. The gap below is real in the test records; how much of it is the engine and how much is the owner, this data cannot separate. Bands under 100 tests are not shown; bands under 5,000 tests are rough estimates.

Best year for a Mercedes-Benz SLC, and the years to avoid

Build year 2016 is highest at 106.4; Build year 2019 is lowest at 81.1 — the gap is 25.3 points.

below 100 is betterabove 100 is worse100 = normal for this model at that age

build year vs the same model at the same age · 100 = as expected

The best build year here is 2016 and the weakest is 2016. Comparing build years sounds simple and is not: within a single year of testing, a car's build year and its age are the same number, so a naive comparison of years is a comparison of ages wearing a disguise. Each year below is measured against the same model at the same age in other cohorts, across six years of testing — 1 of 5 years come out distinguishable from their own model's age norm.

Two limits worth knowing before you act on this. Age, test year and build year are locked together by arithmetic, so the test-year effect is taken from the observed national failure level of each year rather than estimated — it is an adjustment, not a solution.

Mercedes-Benz SLC MOT repair costs

The MOT-failure repair budget per test runs from £17.49 to £33.23, against £54.85 for the test itself.

bigger number = costs morepounds per test, MOT-failing faults only

Multiply how often each component fails on this model by what that repair usually costs, and you get the amount an owner should expect to budget per test for MOT-failing faults only — roughly £17 to £33, on top of the test fee itself. It is a budgeting figure, not a quote: the spread between a set of pads and a set of discs is most of the range.

Prices are modal quotes from a hand-kept catalogue of published UK garage guides — we do not scrape the booking sites, their terms forbid it, so this list is short and updated by hand with a source and date against each line. Each line prices one typical repair in that group, not a full remedy, and only groups our catalogue actually covers are counted. The contrast worth noticing is the second card: the legal maximum for the test has been £54.85 since 2010, while the repairs it uncovers have followed inflation the whole time.

For scale from a different direction: Warrantywise, which sees used-car warranty claims rather than test failures, puts the average claim at £2,052 across the ten highest-claim models it ranks and £539 for Honda, the lowest-claim make in its index (Warrantywise index 2026, 1.6 million claims, cars aged 3–15). Those sit an order of magnitude above the figures in this table, and the gap is the point: a warranty claim is a gearbox or an engine, which almost never fails an MOT, while the faults that do fail one are corrosion, lamps and tyres, which no warranty pays for. The two numbers answer different questions and neither replaces the other.

Mercedes-Benz SLC running costs for a fleet

Vehicles failing at age 8 stand out at 17.0%, against 9.0% at age 5, tested in the same year.

higher = larger sharecompare shares in percentage points

No single year stands out as the point where this model starts costing more: the year-to-year steps in its failure rate are too small or rest on too few tests to name one (D1 rule: a step is named only with at least 2,000 tests on both sides and a jump above 3 percentage points).

Repair spend uses the same modal prices as the section above, so it inherits the same limits: one typical repair per component group, not a full remedy. Downtime is the gap between the failed test and the passed re-test, which is the window a vehicle is legally off the road.

Mercedes-Benz SLC rust problems: where they corrode

Age-standardised corrosion susceptibility is well below the reference at 0.1×, against 1.00× for the national age-standardised rate.

above 1.0× = rusts more than averagebelow 1.0× = rusts less

This Mercedes-Benz SLC virtually never fails on corrosion once age is held constant, and its owners live in areas that are about typical for the models we publish.

Corrosion is the one failure mode that is as much about geography as about the car. We keep the two apart on purpose: a model can look rusty simply because it is popular in Scotland, and a model can look clean simply because it is bought in Surrey. Blending them into a single score would hide which of the two is doing the work.

Exposure is this model's tests weighted by an area corrosion index built from frost days, salt load and distance to the coast — the composite validated at r = 0.42 against corrosion defects we actually record. It is published as a rank, not a raw score, because every mainstream model skews towards low-corrosion areas for the simple reason that most of Britain's cars are in the south. Susceptibility is standardised to the national age profile, so an old fleet does not get labelled a rusty model.

Does a Mercedes-Benz SLC advisory become a failure?

Tyres are highest at 10.2%; Non-component advisories are lowest at 0.0% — the gap is 10.2 percentage points.

higher = more likelypercentage is the observed transition probability

chance the same component fails at the next MOT, given an advisory now

This is the question an advisory note actually raises, and it needs six years of test history to answer. We followed the same vehicles from one MOT to the next across 2019–2024 and measured how often a component that was merely advised came back as a genuine failure at the next test.

Read it as a budgeting horizon, not a prophecy: the most likely component above turns into a failure for about 10 in 100 cars, and the median gap is 12 months and roughly 5,155 miles. The rest were repaired, sold, scrapped, or simply held. Rows with fewer than 500 tracked advisories are not shown.

What will fail next on a Mercedes-Benz SLC?

Tyres after a advisory at age 3-5 are highest at 9.9%; Noise, emissions and leaks after a passed at age <3 are lowest at 0.6% — the gap is 9.3 percentage points.

higher = more likelypercentage is the observed transition probability

The same chains, cut differently: given a car's age and how its last test went, which component most often causes trouble at the following one.

The pattern that repeats across every family: a failure at one test roughly doubles the chance of a failure on the same component at the next one, and an advisory sits about half-way between a clean pass and a failure. Age bands in years; probabilities are per car, not per defect item.

Mercedes-Benz SLC ownership: what six years of MOTs show

The ten-day re-test pass rate is highest at 52.6%; The later re-test pass rate is lowest at 1.8% — the gap is 50.8 percentage points.

higher = larger sharecompare shares in percentage points

Failing is usually a same-week event, not a disaster. Of 3,937 failures followed through to their re-test, 45.57% were repaired and passed the same day and 52.63% within ten days; the median gap is 1 day. 6,074 defect items were cleared in the process.

Per mile driven, not per year. Dividing failures by the miles that actually went onto the odometers between consecutive tests gives 0.279 failures per 10,000 miles, on a median of 3,603 miles a year across 8,793 chains. This is the number to compare between models — an annual rate quietly rewards cars that barely leave the drive.

Two populations hide inside one model. 62.7% of these cars strung together three or more tests with nothing recorded at all, while 11.11% carried the same advisory three times or more — the same fault, noted, ignored, noted again. When you buy used you are buying one of those two histories, and the MOT record shows which.

Odometer anomalies: 0.728% of 8,793 chains show a reading lower than the previous test, with a median drop of 8,989 miles. We call this an anomaly and not fraud on purpose — instrument swaps, imports, unit mix-ups and keying errors all land in the same bucket. Obvious typos (drops under 100 miles or over 90% of the reading) are already excluded.

Mercedes-Benz SLC safety recalls and how to check yours

DVSA recall campaigns stand out at 16.

bigger number = more recorded casescompare like-for-like scope, not sample size alone

recall campaigns launched per year

DVSA lists 16 safety recall campaigns for the Mercedes-Benz SLC, covering roughly 719,857 vehicles in total. A recall is the manufacturer fixing a fault for free, so an open recall on your car costs nothing to clear.

Counter-intuitive, and measured on our own data: across the 25 families published here, more recalls go with a lower MOT Risk Index (r = −0.52). Heavily recalled models are not worse cars in the test bay — an active manufacturer removes the fault before it becomes an MOT failure.

Check whether a specific car has an outstanding recall — free, by registration — at DVSA's recall service. Source: DVSA vehicle safety recalls (check-vehicle-recalls.service.gov.uk), OGL.

Mercedes-Benz SLC MOT: quick answers

Mercedes-Benz SLC MOT Risk Index is well below the reference at 70.9, against 100 for a car with the same age profile.

below 100 is betterabove 100 is worse100 = normal for this model at that age

What is the Mercedes-Benz SLC first-time MOT pass rate?

86.29% of first attempts passed in 2024 (8,972 tests). This is the first-time figure: retests after repair are excluded. Basis: first-time, excluding retests.

Why does this number differ from other sites?

Other sites often report a pass rate that includes retests or counts all attempts. Our 13.71% figure is the first-time initial failure rate, using 8,972 primary tests as the denominator (first-time, excluding retests). The age-adjusted MOT initial-failure ratio 70.9 is shown separately because raw rates compare fleet age as well as cars.

Compare the Mercedes-Benz SLC with other cars

Volvo XC40 is highest at 71.7; Suzuki Celerio is lowest at 70.0 — the gap is 1.7 points.

below 100 is betterabove 100 is worse100 = normal for this model at that age

Same brand

All Mercedes-Benz MOT statisticsMercedes-Benz GLE MOT statsMercedes-Benz SLK MOT stats

Similar risk

Land Rover Range Rover (index 70.9)Volvo XC40 (index 71.7)Suzuki Celerio (index 70.0)

Same size class

how Ford Tourneo Custom compareshow Ford Edge compareshow Peugeot 407 compares

By build year

Mercedes-Benz SLC 2016Mercedes-Benz SLC 2017Mercedes-Benz SLC 2018Mercedes-Benz SLC 2019Mercedes-Benz SLC 2020

By area

Mercedes-Benz SLC MOT failure rate by postcode area

By failure group

Mercedes-Benz SLC brakes failuresMercedes-Benz SLC vehicle identification failuresMercedes-Benz SLC lamps, reflectors and electrics failuresMercedes-Benz SLC noise, emissions and leaks failuresMercedes-Benz SLC road wheels failuresMercedes-Benz SLC steering failuresMercedes-Benz SLC suspension failuresMercedes-Benz SLC tyres failuresMercedes-Benz SLC visibility failures