MOT performance

Mercedes-Benz SLK diesel: MOT pass rate and common failures

Of 32,488 MOT tests on diesel Mercedes-Benz SLKs in 2023–2024 (on average 8.7 years old at test, median 51,314 miles), 77.8% passed first time, against 73.0% of 101,318 petrol Mercedes-Benz SLK tests. Allowing for age, mileage and fuel, diesel Mercedes-Benz SLKs failed 7% less often than comparable cars — 0.93× against 0.82× for the Mercedes-Benz SLK as a whole.

32,488 MOT tests on 16,143 vehicles, 2023–2024 · Source: DVSA (Open Government Licence) · Analysis: 73 Auto

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At a glance

Mercedes-Benz SLK diesel MOT results at a glance
Figure	Value	Basis
First-time pass rate	77.8%	±0.5 pts (95%), n = 32,488
All Mercedes-Benz SLKs	74.2%	n = 133,811
Failures vs similar cars	0.93×	same age, mileage and fuel = 1.00; Mercedes-Benz SLK overall 0.82×
Tests with a dangerous defect	8.1%	n = 32,488
Average age at test	8.7 years	n = 32,488
Registration years covered	1999–2018	DVSA first-use date

Diesel against the other Mercedes-Benz SLK fuels

Official DVSA test results by fuel, with 73 Auto's adjusted ratio (failures against cars of the same age, mileage and fuel). The diesel cars were tested 6.4 years younger on average than the petrol ones, so the raw pass rates partly reflect age; the adjusted column doesn't.

Mercedes-Benz SLK MOT results by fuel
Fuel	Tests	Average age	First-time pass	vs similar cars	Dangerous
Petrol	101,318	15.1 yrs	73.0%	-20%	6.3%
Diesel	32,488	8.7 yrs	77.8%	-7%	8.1%

Where diesel Mercedes-Benz SLKs differ

Steering: diesel Mercedes-Benz SLKs failed 75% less often than the Mercedes-Benz SLK overall, relative to comparable cars (0.10× vs 0.39×).
Body, chassis and structure: diesel Mercedes-Benz SLKs failed 60% less often than the Mercedes-Benz SLK overall, relative to comparable cars (0.11× vs 0.28×).
Tyres: diesel Mercedes-Benz SLKs failed 39% more often than the Mercedes-Benz SLK overall, relative to comparable cars (1.54× vs 1.11×).
Suspension: diesel Mercedes-Benz SLKs failed 30% more often than the Mercedes-Benz SLK overall, relative to comparable cars (1.30× vs 1.00×).

Mercedes-Benz SLK diesel MOT failures by area, against the model overall
Area	Diesel (vs similar)	All Mercedes-Benz SLKs (vs similar)
Tyres	8.9% (+54%)	6.3% (+11%)
Suspension	8.6% (+30%)	10.3% (Same)
Brakes	3.5% (-31%)	5.6% (-29%)
Lights, reflectors and electrical	3.4% (-54%)	7.6% (-42%)
Driver's view of the road	1.5% (-56%)	2.9% (-46%)
Noise, emissions and leaks	1.2% (-35%)	2.4% (-43%)
Road wheels	0.4% (+51%)	0.4% (+40%)
Registration plates and VIN	0.4% (+50%)	0.4% (-13%)
Seat belts and airbags	0.4% (-37%)	1.1% (-16%)

Most common diesel Mercedes-Benz SLK failure items

Most common diesel Mercedes-Benz SLK MOT failure items
Item	Area	Share of tests
Coil spring: fractured or broken	Suspension	4.27%
Condition: has ply or cords exposed	Tyres	2.96%
Tread depth: tread depth below requirements of 1.6mm	Tyres	2.76%
Condition: has a cut in excess of the requirements deep enough to reach the ply or cords	Tyres	1.80%
Ball joint: ball joint excessively worn	Suspension	1.36%

Pass rate by age, by fuel

Mercedes-Benz SLK MOT pass rate by age and fuel
Age at test (years)	diesel pass rate (tests)	petrol pass rate (tests)
3-4	—	91.6% (3,322)
5-6	83.4% (3,788)	88.4% (6,081)
7-8	80.4% (10,457)	86.8% (5,837)
9-10	76.1% (13,178)	81.7% (6,433)
11-12	72.2% (4,906)	76.5% (10,731)
13-15	—	69.6% (15,521)
16+	—	67.6% (52,755)

Mercedes-Benz SLK by registration year

Registration-year pages cover every fuel of that year.

What this does and doesn't tell you

Fuel is DVSA's recorded fuel type; plug-in and self-charging hybrids are grouped as hybrid. A difference between fuels can come from the engines themselves, or from how the cars are used — diesels typically cover more miles, and the adjusted ratio allows for mileage band but not for every difference in use. For one car, its own MOT history is the better guide: see MOT check.

Check a specific diesel Mercedes-Benz SLK

Enter a UK registration to see that car's own MOT history and what it is likely to cost to own. Your first check is free and shows the vehicle summary and its headline ownership cost. The category-by-category breakdown is part of a paid check.

UK number plate or 17-character VIN

About this data. These are MOT test results, not a measure of mechanical reliability: a car's MOT outcome reflects its condition on the day, which depends on how it has been maintained and driven as well as how it was built. Figures cover class 4 vehicles (cars and light vans), normal tests only (retests excluded), outcomes pass, fail and pass after rectification at the station; vehicles at least 2.5 years old at test. Tests from 2023-01-01 to 2024-12-30. “Compared with similar cars” means compared with the national rate for cars of the same age, mileage band and fuel. Contains public sector information licensed under the Open Government Licence v3.0. Makes and models are matched to 73 Auto's vehicle catalogue; tests that can't be matched are left out rather than guessed. See how the MOT figures are produced.