Mercedes-Benz SLK reliability, MPG and running costs
Figures updated
The Mercedes-Benz SLK is a sports car. In 2024 MOT tests it scored 121 for reliability (100 is average), ranking 146 of 442, and 27.5% failed first time against a UK average of 28.5%. Its most common MOT failure is coil spring (5.6% of tests).
Ranked 146 of 442 cars in the 2024 MOT Reliability League, and 6 of 7 sports cars
In 2024, 46,780 Mercedes-Benz SLKs aged 3 to 20 had an MOT and 27.5% failed first time (UK average 28.5%). Taking age and mileage into account, the Mercedes-Benz SLK is 17% less likely to fail than the average car of the same age and mileage.
First-time fail rate
27.5%
UK 28.5%
Fail rate at 3 years
–
UK 12.7%
Average miles a year
5,000
Typical age at test: 13 years
Mercedes-Benz SLK MOT failure rate by age
Most common Mercedes-Benz SLK MOT faults
- Coil spring: fractured or broken5.6% of tests
- Ball joint: ball joint excessively worn3.4% of tests
- Tread depth: tread depth below requirements of 1.6mm2.2% of tests
- Condition: has ply or cords exposed1.8% of tests
- Malfunction indicator lamp: inoperative or indicates a malfunction1.7% of tests
- Rigid brake pipes: excessively corroded1.5% of tests
What the Mercedes-Benz SLK fails on
| Area | Tests failing | vs similar cars |
|---|---|---|
| Suspension | 13.3% | ▲ 1.2× as often |
| Tyres | 6.6% | About average |
| Lights and electrics | 6.2% | ▼ 55% less often |
| Brakes | 6.2% | ▼ 24% less often |
| Visibility | 2.5% | ▼ 53% less often |
| Exhaust and emissions | 2.4% | ▼ 39% less often |
| Seat belts and airbags | 1.3% | 1.1× as often |
| Body and structure | 1.1% | ▼ 76% less often |
| Steering | 0.9% | ▼ 62% less often |
| Wheels | 0.5% | ▲ 1.4× as often |
What MPG does the Mercedes-Benz SLK do?
Official economy for the Mercedes-Benz SLK ranges from 23.5 to 64.2mpg across the 89 versions listed by the Vehicle Certification Agency (2004–2016). A typical petrol version manages 38.7mpg and a typical diesel 56.5mpg. Expect 10–15% less in real-world driving.
Work out a journey's fuel costHow much is road tax on a Mercedes-Benz SLK?
Any Mercedes-Benz SLK first registered from April 2017 pays the standard rate of £200 a year after its first year (2026/27 rates). A Mercedes-Benz SLK registered between March 2001 and March 2017 is taxed on its CO2: £35 to £790 a year.
Work out tax for a specific carMercedes-Benz SLK specs and running costs
Official figures for 89 versions sold in the UK between 2004 and 2016.
Fuel types
Diesel, Petrol
Official economy
23.5–64.2 mpg
CO2
114–288 g/km
| Version | Fuel | Economy | CO2 | Car tax |
|---|---|---|---|---|
| SLK SLK 250 d with 17'' & 18'' rear wheelsA9 · listed 2016 | Diesel | 64.2 mpg | 114g | £35 |
| SLK AMG SLK 55 with 20'' rear wheelsA7 · listed 2016 | Petrol | 33.6 mpg | 195g | £410 |
| SLK SLK 200 with 18'' rear wheelsA9 · listed 2016 | Petrol | 47.9 mpg | 137g | £200 |
| SLK SLK 200 with 18'' rear wheelsM6 · listed 2016 | Petrol | 43.5 mpg | 150g | £225 |
| SLK SLK 300 with 18'' rear wheelsA9 · listed 2016 | Petrol | 47.1 mpg | 138g | £200 |
| SLK SLK 250 CDI with 17" & 18" rear wheels ECO Start/StopA7 · listed 2015 | Diesel | 56.5 mpg | 132g | £200 |
| SLK SLK 250 d with 17'' & 18'' rear wheels ECO Start/StopA9 · listed 2015 | Diesel | 64.2 mpg | 114g | £35 |
| SLK SLK 200 with 17" & 18" rear wheels ECO Start/StopM6 · listed 2015 | Petrol | 41.5 mpg | 158g | £275 |
| SLK SLK 200 with 17" & 18" rear wheels ECO Start/StopA7 · listed 2015 | Petrol | 43.5 mpg | 151g | £275 |
| SLK SLK 250 with 17" & 18" rear wheels ECO Start/StopA7 · listed 2015 | Petrol | 42.8 mpg | 153g | £275 |
| SLK SLK 250 with 17" & 18" rear wheels ECO Start/StopM6 · listed 2015 | Petrol | 38.7 mpg | 169g | £325 |
| SLK SLK 350 with 17" & 18" rear wheels ECO Start/StopA7 · listed 2015 | Petrol | 39.8 mpg | 167g | £325 |
| SLK SLK 55 AMG with 18" rear wheelsA7 · listed 2015 | Petrol | 33.6 mpg | 195g | £410 |
| SLK SLK 250 CDI with 17" & 18" rear wheels ECO Start/StopAutomatic · listed 2014 | Diesel | 56.5 mpg | 132g | £200 |
| SLK SLK 200 with 17" & 18" rear wheels ECO Start/StopAutomatic · listed 2014 | Petrol | 43.5 mpg | 151g | £275 |
Economy and CO2 are official NEDC (before 2018) or WLTP figures. Car tax is the yearly rate at current rates for a car first registered in the year listed, before any expensive car supplement. Showing the 15 most recent of 89 versions.
What a Mercedes-Benz SLK costs to fuel
- petrol, typical official 38.7mpg…
- diesel, typical official 56.5mpg…
Official figures are usually 10–15% better than real-world driving.
Work out a journey in a Mercedes-Benz SLKBuying a used Mercedes-Benz SLK?
Check the MOT history of the exact car: every result, advisory and mileage reading, free.
Compare the Mercedes-Benz SLK with other sports cars
Reliability, economy, car tax and running costs side by side.
Other Mercedes-Benz models
Frequently asked questions
›Is the Mercedes-Benz SLK reliable?
Its MOT record is better than average: the Mercedes-Benz SLK is 17% less likely to fail than the average car of the same age and mileage, with a reliability score of 121 in our 2024 league (100 is average).
›What are common problems with the Mercedes-Benz SLK?
The most common MOT fault is “Coil spring: fractured or broken”, found in 5.6% of tests.
›What MPG does the Mercedes-Benz SLK do?
Official economy for the Mercedes-Benz SLK ranges from 23.5 to 64.2mpg across the 89 versions listed by the Vehicle Certification Agency (2004–2016). A typical petrol version manages 38.7mpg and a typical diesel 56.5mpg. Expect 10–15% less in real-world driving.
›How much is road tax on a Mercedes-Benz SLK?
Any Mercedes-Benz SLK first registered from April 2017 pays the standard rate of £200 a year after its first year (2026/27 rates). A Mercedes-Benz SLK registered between March 2001 and March 2017 is taxed on its CO2: £35 to £790 a year.
›How many Mercedes-Benz SLKs fail their MOT?
27.5% of Mercedes-Benz SLKs aged 3 to 20 failed their MOT first time in 2024.
Sources: DVSA anonymised MOT tests 2024, all versions of the Mercedes-Benz SLK combined (Open Government Licence v3.0); official economy and CO2 from Vehicle Certification Agency data, © Crown copyright. VCA cannot accept liability for its accuracy. How we calculate the league.