Mercedes-Benz B-Class 2018: MOT failure rate for its age

12.5% of 15,953 MOT tests of the Mercedes-Benz B-Class first registered in 2018 failed at the first attempt (2019–2024; retests excluded). Against this model's own normal rate at the same ages the index is 100.4 (95% CI 96.0–104.8; 100 = normal for this model at that age): the 2018 build year is no different from other years of the same model at the same age.

Mercedes-Benz B-Class built in 2018 at a glance
Measure	Value	Unit	Compared with	Years	Tests
Failed first time	12.5	%	all ages tested	2019–2024	15953
Index against this model at the same age (95% CI 96.0–104.8)	100.4	index	100 = normal for this model at that age	2019–2024	15953
Rank among this model's 16 build years	10	of 16	1 = fails least for its age	2019–2024	15953
Tested in 2024	3982	tests	median 34,665 miles	2024	3982

Built 2018 against Mercedes-Benz B-Class normal for the age: first-time MOT failure share at each age, age 3: 11.4% vs 10.3%; age 4: 11.6% vs 11%; age 5: 13% vs 12.9%; age 6: 14% vs 15.6%. Axis from 0% to 20%. DVSA MOT bulk data, 2019–2024.

Check a 2018 Mercedes-Benz B-Class by registration · All Mercedes-Benz B-Class MOT statistics · Download the build-year table (CSV)

Data release dvsa-2024-v2 (24 Sep 2026) · page updated 30 Sep 2026 · full dataset (v5).

How does the 2018 Mercedes-Benz B-Class fail at each age?

Cars built in 2018 were tested at ages 3 to 6 between 2019 and 2024. Each row compares their first-time failure share with what this model normally shows at that age, after allowing for the overall failure level of each test year.

Mercedes-Benz B-Class built 2018: first-time MOT failure by age, against the model's normal rate at that age (2019–2024)
Age	Tests	Failed, %	95% interval	Normal for this model at that age, %	Index (100 = normal)
3	3,971	11.4	10.4–12.4	10.3	110.2
4	4,020	11.6	10.6–12.6	11	105.7
5	3,980	13	12–14.1	12.9	100.8
6	3,982	14	12.9–15.1	15.6	89.8

Source: DVSA MOT bulk data · Window: 2019–2024 · n = 15,953 (initial tests) · Method: normal rate = this model's first-time failure share at that age across its build years (cells of 400+ tests), adjusted for each test year's overall level; cells of 30+ tests, under 500 marked rough · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV

What fails most on the 2018 Mercedes-Benz B-Class?

The most common failure group on cars built in 2018 is tyres: 7.5 items per 100 first tests, against 8.6 across all build years of the Mercedes-Benz B-Class. These counts are not age-adjusted: cars built in 2018 were tested at ages 3 to 6.

Failure items per 100 first tests, Mercedes-Benz B-Class built 2018 against the Mercedes-Benz B-Class in all build years (2019–2024, not age-adjusted)
Failure group	Built 2018, per 100	All build years, per 100	Items
Tyres	7.5	8.6	1,202
Lamps, reflectors and electrical equipment	4.3	12.5	692
Visibility	3.9	6.5	632
Brakes	1.5	9.8	234
Suspension	0.8	12.4	135

Source: DVSA MOT bulk data · Window: 2019–2024 · n = 16,054 (initial tests of this build year) · Method: failure items grouped by DVSA's top-level defect groups, per 100 initial tests; groups with 30+ items · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV

How does 2018 compare with the years around it?

Among the 16 published build years of the Mercedes-Benz B-Class, 2018 ranks 10 (1 = fails least for its age). 2017: index 96.9. 2019: index 85.1.

Mercedes-Benz B-Class build years: index against the model at the same age (2019–2024)
Build year	Index (100 = normal)	95% interval	Verdict	Tests
2005	99.2	94.4–104.0	no different (rough estimate)	3,756
2006	101.1	98.7–103.5	no different	16,074
2007	101.6	99.3–103.8	no different	18,838
2008	104.7	102.6–106.8	worse	22,898
2009	103.6	101.7–105.6	worse	27,243
2010	106.7	104.7–108.8	worse	28,176
2011	116.6	114.0–119.2	worse	21,943
2012	95.3	93.3–97.3	better	33,753
2013	93.6	91.6–95.5	better	39,423
2014	100.2	98.3–102.2	no different	46,572
2015	94.5	92.0–96.9	better	33,910
2016	98.1	95.3–100.8	no different	32,176
2017	96.9	93.8–99.9	better	30,281
2018	100.4	96.0–104.8	no different	15,953
2019	85.1	80.3–89.9	better	12,587
2020	86.7	79.2–94.2	better	5,645

Source: DVSA MOT bulk data · Window: 2019–2024 · n = 389,228 (initial tests) · Method: observed failures against those expected for the same model at the same ages, test-year level adjusted; verdict follows the printed one-decimal bound · Updated: 30 Sep 2026 · Release: dvsa-2024-v2 · CSV

How to cite this page

MOT Risk Index (2026). Mercedes-Benz B-Class 2018 MOT statistics (data release dvsa-2024-v2; full dataset motriskindex-families-2024-v5, DOI 10.5281/zenodo.22975051), updated 30 September 2026. motriskindex.co.uk/cars/mercedes-b-class/2018/

How every figure is calculated: methodology. Age, test year and build year are tied together (age = test year − build year), so the test-year level is taken as observed, not estimated.

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