Mercedes SLK Reliability: Common Problems and Years to Avoid
What the Mercedes SLK fails its MOT on, with rough repair costs, and how each model year's MOT pass rate compares with other cars of the same age. Based on 128,923 MOT tests across 21 model years (DVSA data for tests carried out in 2024, retests included).
Segment: premium performance | Fuel: Petrol, Diesel
82%
Mercedes SLK pass rate
87%
Mercedes average
82%
All-model average
The Mercedes SLK has an average MOT pass rate of 82%, which is 5 points below the Mercedes average and equal to the average across all models in our data. Newer Mercedes SLKs pass their MOT more often than older ones, by 4 percentage points on average, which is mostly down to age and wear.
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What the Mercedes SLK Fails Its MOT On
Of the 15,228 MOT tests on the Mercedes SLK that failed at the first attempt in 2025, the share that failed on each part of the test, next to the share for all cars and vans of the same ages. A test that failed on two areas counts in both.
Suspension
44%Cars and vans the same age: 38% · Typical repair £150-£600
Lights and electrics
29%Cars and vans the same age: 45% (the SLK fails on this less often) · Typical repair £15-£200
Tyres
22%Cars and vans the same age: 17% (the SLK fails on this more often) · Typical repair £50-£300
Brakes
22%Cars and vans the same age: 26% · Typical repair £80-£450
Windscreen, wipers and mirrors
12%Cars and vans the same age: 16% (the SLK fails on this less often) · Typical repair £10-£350
The 3 single faults it failed on most
- Coil spring: fractured or broken (18% of failed tests, suspension)
- Suspension arm ball joint excessively worn (10% of failed tests, suspension)
- Tyre tread depth below the 1.6mm limit (7% of failed tests, tyres)
Source: CarCostCheck analysis of DVSA anonymised MOT test results and failure items for 2025: first attempt at each MOT, fail and pass-after-repair defects, DVSA's defect categories (names shortened). Repair costs are rough UK ranges, not quotes. Method and national figures: MOT failure reasons 2025.
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Mercedes SLK Years to Avoid
Every car in the 2024 MOT data was tested at the same age as the other cars first registered that year, so each SLK year is compared with all cars from the same year. Years with 1,000+ tests that were at least three years old are included.
Failed more often than cars their age
No year passed 3 or more points less often than other cars of the same age.
A lower pass rate means that year failed its MOT more often in 2024; it does not mean every car from that year is bad. Old cars still on the road are often the best-kept ones, which can lift the pass rates of the oldest years. How a car has been looked after matters more, so check the MOT history of the car you are looking at.
Mercedes SLK Reliability by Year
MOT pass rate for each model year, from DVSA data for tests carried out in 2024 (retests included). Newer cars usually pass more often simply because they are younger. All Cars is the pass rate of every car first registered that year, with the gap in points. Highest and lowest are marked among years with 100+ tests that were at least three years old when tested. Fuel and engine size are a guide only.
| Year | Fuel | Engine | Pass Rate | Fail Rate | All Cars |
|---|---|---|---|---|---|
| 2016 | Petrol | 5.5L | 89% | 11% | 86% (+3) |
| 2015 | Petrol | 5.5L | 87% | 12% | 84% (+3) |
| 2014 | Petrol | 5.5L | 87% | 13% | 82% (+5) |
| 2013 | Petrol | 5.5L | 85% | 15% | 80% (+5) |
| 2012 | Diesel | 2.5L | 84% | 15% | 79% (+5) |
| 2011 | Petrol | 1.8L | 85% | 15% | 77% (+8) |
| 2010 | Petrol | 2.3L | 80% | 20% | 75% (+5) |
| 2009 | Petrol | 2.3L | 81% | 19% | 75% (+6) |
| 2008 | Petrol | 1.8L | 80% | 19% | 74% (+6) |
| 2007 | Petrol | 1.8L | 79% | 21% | 73% (+6) |
| 2006 | Petrol | 1.8L | 79% | 20% | 73% (+6) |
| 2005 | Diesel | 2.0L | 78% | 21% | 73% (+5) |
| 2004 | Petrol | 2.3L | 78% | 21% | 72% (+6) |
| 2003 | Petrol | 2.3L | 78% | 20% | 72% (+6) |
| 2002 | Petrol | 2.3L | 81% | 18% | 73% (+8) |
| 2001 | Petrol | 2.3L | 82% | 17% | 73% (+9) |
| 2000 | Petrol | 2.3L | 79% | 20% | 74% (+5) |
| 1999 | Petrol | 2.3L | 79% | 20% | 75% (+4) |
| 1998 | Petrol | 2.3L | 79% | 21% | 76% (+3) |
| 1997 | Petrol | 2.3L | 81% | 18% | 76% (+5) |
| 1996 | Petrol | 2.3L | 76% | 24% | - |
Mercedes SLK Running Costs
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Mercedes SLK FAQ
What are the most common Mercedes SLK problems?
In 2025, MOT tests on the Mercedes SLK that failed at the first attempt most often failed on suspension (44% of the 15,228 failed tests), lights and electrics (29%) and tyres (22%). The single most common fault was "Coil spring: fractured or broken" (18%). Across 128,923 MOT tests (DVSA MOT data for tests in 2024, retests included), 82% ended in a pass.
Is the Mercedes SLK reliable?
The Mercedes SLK has an average MOT pass rate of 82%, from 128,923 MOT tests (DVSA MOT data for tests in 2024, retests included). Comparing each model year with all cars first registered the same year, so that age is allowed for, it passed 5 points more often on average, a better than average result for its age.
Which Mercedes SLK years should I avoid?
No Mercedes SLK year with 1,000+ tests passed 3 or more points less often than all cars first registered the same year (DVSA MOT data for tests in 2024, retests included). The years that passed most often for their age were the 2001 (82% of 4,005 tests passed, against 73% for all 2001 cars), the 2011 (85% of 5,660 tests passed, against 77% for all 2011 cars) and the 2002 (81% of 3,692 tests passed, against 73% for all 2002 cars). A year's pass rate does not tell you about one car, so check the MOT history of the car you are buying.
How much does it cost to fix common Mercedes SLK faults?
As a rough guide, brake work on a Mercedes SLK typically costs £80-£450 and suspension repairs £150-£600, while exhaust and emissions fixes can cost £80-£800. Lighting and wiper fixes are usually under £200.
Check a Specific Mercedes SLK
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Other Mercedes Models
Common problems pages for other Mercedes models