Mercedes-Benz B — MOT statistics 2024

The Mercedes-Benz B failed 10.99% of 1,065 first MOT attempts in 2024 ("first-time", excluding retests). Adjusted for the age of the fleet, its initial-failure ratio is 74.7 (100 = expected for its age profile). This car fails its MOT about 25% less often than expected for its age. Small sample — treat with care.

Age-adjusted peer: Audi Q3 (index 75.0) — the two published results are 0.3 index points apart.

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

Suspension is well below the reference at 2.4 per 100 tests, against 4.5 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 B MOT advisories: what gets flagged

Tyres are highest at 33.4 per 100 tests; Suspension is lowest at 1.8 per 100 tests — the gap is 31.6 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 B 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 8.2 percentage points. 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 4,596 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 changes little here (+3.0 points): this fleet is driven about as much as the vehicles it is compared with. 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 B 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 B perform as it gets older?

The B at age 5 is well below the reference at 7.7%, against 15.1% for all vehicles of the same age.

higher = larger sharecompare shares in percentage points

Chart axes: car age, years · failure-rate scale 0–19%.

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

How dangerous are Mercedes-Benz B MOT failures?

Major defects are well below the reference at 15.8 per 100 tests, against 52.8 per 100 tests nationally.

higher bar = fails more oftenrate per 100 tests

Chart values: Minor 4.7 · Major 15.8 · Dangerous 7.2.

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 B MOT matter?

Jun is highest at 21.4%; May is lowest at 11.6% — the gap is 9.7 percentage points.

higher = larger sharecompare shares in percentage points

Chart scale: 10%–33%.

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

Takeaway: the spread between best and worst month is 9.7 percentage points — noticeable seasonality. 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 B average mileage by age

At age 4, the middle half of Bs runs from 17,952 miles to 31,634 miles, against 23,660 miles as the median.

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

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

Within the same age group, split by odometer (2024 MOTs), so this separates wear from age: at ages 3–5, 8.3% of those with under 40,000 miles failed first time versus 15.2% of those with 40,000–70,000 miles.No clear mileage gap inside this age group, among cars still being tested.

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

A typical 4-year-old B has ~23,660 miles on the clock. Much more — ask why; much less — check for gaps in the MOT history.

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

Too few tests in any single postcode area to name one, so this is the wider picture across 4,602 tests, 2019-2024.

Raw pass/fail rates, not age-adjusted: fleets differ by region. England is split north of Sheffield, between Sheffield and Oxford, and south of it.

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

By age 12 is well below the reference at 5.3%, 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 12, only about 5% as many cars of this family present for MOT as at ages 4–6 (reference n≈1,243); survivors still fail at 28.8% vs 8.1% at age 4. Older cars that still appear are a selected subset — weaker ones have already left.

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

Bought at age 8 is highest at 4.3 years; Bought at age 12 is lowest at 0.5 years — the gap is 3.8 years.

bigger number = longer remaining lifeyears on the observed survival curve

estimateEstimate only — not a warranty: a typical 10-year-old example of this family has at least 2.4 expected years of further MOT-present life. The curve is observed only until age 12, so the true figure is likely higher.

Mercedes-Benz B faults that come together

Brakes + Lamps & electrical stand out at 4.95×, against 1.00× if the faults were independent.

above 1.0× = more than expectedbelow 1.0× = less

Defects in «Brakes» and «Lamps, reflectors and electrical equipment» appear together 4.95× more often than chance (23 co-occurrences in the same test; 66 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 B?

Cars driven under 5,000 miles a year is well below the reference at 10.5%, against 24.4% 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 10.5% vs 24.4% for 8–12k miles/year — 13.9 pp lower (n_low=516, n_normal=904). 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. Diesel alone: 11.0% low-use vs 24.7% normal (-13.7 pp).

Which Mercedes-Benz B engine is best?

diesel 1.5–1.8 is highest at 115.6; petrol 1.5–1.8 is lowest at 78.8 — the gap is 36.8 points.

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

No engine band clearly fails less or more for its age: the bands are within 5 index points of each other, or their 95% intervals overlap, so this page does not name a best or worst engine.

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 B, and the years to avoid

Build year 2014 is highest at 95.3; Build year 2019 is lowest at 41.3 — the gap is 54.0 points.

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

The best build year here is 2019 and the weakest is 2019. 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 2 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 B MOT repair costs

The MOT-failure repair budget per test runs from £27.68 to £52.59, 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 £28 to £53, 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 B running costs for a fleet

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 B rust problems: where they corrode

Salt-belt exposure is well below the reference at 37th percentile, against 50th percentile as the middle of published models.

higher = larger sharecompare shares in percentage points

This Mercedes-Benz B has too few tests to judge for 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.

What will fail next on a Mercedes-Benz B?

Tyres after a failure at age 3-5 are highest at 8.8%; Lamps, reflectors and electrical equipment after a passed at age 3-5 are lowest at 3.7% — the gap is 5.1 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 B ownership: what six years of MOTs show

The same-day re-test pass rate is highest at 52.0%; The later re-test pass rate is lowest at 1.9% — the gap is 50.1 percentage points.

higher = larger sharecompare shares in percentage points

Failing is usually a same-week event, not a disaster. Of 585 failures followed through to their re-test, 51.97% were repaired and passed the same day and 46.15% within ten days; the median gap is 0 days. 993 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 0.287 failures per 10,000 miles, on a median of 5,567 miles a year across 1,693 chains. This is the number to compare between models — an annual rate quietly rewards cars that barely leave the drive.

Odometer anomalies: 1.055% of 1,706 chains show a reading lower than the previous test, with a median drop of 26,560 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 B MOT: quick answers

Mercedes-Benz B MOT Risk Index is well below the reference at 74.7, 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 B first-time MOT pass rate?

89.01% of first attempts passed in 2024 (1,065 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 10.99% figure is the first-time initial failure rate, using 1,065 primary tests as the denominator (first-time, excluding retests). The age-adjusted MOT initial-failure ratio 74.7 is shown separately because raw rates compare fleet age as well as cars.

Compare the Mercedes-Benz B with other cars

BMW X1 is highest at 75.1; Chrysler 300 is lowest at 74.3 — the gap is 0.8 points.

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

Same brand

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

Similar risk

Audi Q3 (index 75.0)BMW X1 (index 75.1)Chrysler 300 (index 74.3)

Same size class

how Citroen C15 compareshow Vauxhall Omega compareshow Vauxhall Cavalier compares

By build year

Mercedes-Benz B 2014Mercedes-Benz B 2019

By area

Mercedes-Benz B MOT failure rate by postcode area

By failure group

Mercedes-Benz B body, chassis and structure failuresMercedes-Benz B brakes failuresMercedes-Benz B lamps, reflectors and electrics failuresMercedes-Benz B noise, emissions and leaks failuresMercedes-Benz B seat belts and airbags failuresMercedes-Benz B suspension failuresMercedes-Benz B tyres failuresMercedes-Benz B visibility failures