The picture
Slk: middle-of-the-pack on first-time pass
Across 71,871 MOT tests, the Slk returns 76.7% first-time pass — roughly in line with the UK fleet average. The single most-logged Major fail is a broken or weak spring. Tyre tread under the limit and windscreen damage round out the top three. Average tested mileage sits at 69,863, 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.
Top ten reasons for rejection.
- 01
A spring or spring component fractured or seriously weakened
3,452 occurrences · 4.8% of tests
- 02
Tyre tread depth not in accordance with the requirements
1,894 occurrences · 2.6% of tests
- 03
Windscreen or window damaged or seriously discoloured but not adversely affecting driver's view
1,790 occurrences · 2.5% of tests
- 04
A suspension pin, bush or joint excessively worn
1,632 occurrences · 2.3% of tests
- 05
Brake pipe damaged or excessively corroded
1,575 occurrences · 2.2% of tests
- 06
Headlamp reflector or lens slightly defective
1,450 occurrences · 2.0% of tests
- 07
A tyre cords visible or damaged
1,161 occurrences · 1.6% of tests
- 08
A suspension joint dust cover severely deteriorated
947 occurrences · 1.3% of tests
- 09
A tyre seriously damaged
867 occurrences · 1.2% of tests
- 10
The aim of a headlamp is not within limits laid down in the requirements
760 occurrences · 1.1% 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 4 failures
£260–£665
If every one of this Slk'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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Tools that pre-empt a retest.
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.
Buying or keeping a Slk?
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 Slk 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.