MERCEDES S-CLASS (2018)
Running costs, common problems, and reliability data based on 6,518 real MOT tests in 2024.
MOT Pass Rate
94%
Total Tests (2024)
6,518
Avg Mileage
75,456 mi
Est. Annual Cost
£2,037
Is the 2018 MERCEDES S-CLASS reliable?
Excellent reliability. Very few MOT failures. That's 12 points above the national average of 82%. It also outperforms the MERCEDES brand average of 87%.
At 6 years old, 94% of MERCEDES S-CLASSs from 2018 passed their MOT first time in 2024. That's based on 6,518 tests across the UK. The average mileage at this age is 75,456 miles.
How does the 2018 MERCEDES S-CLASS compare?
Mileage Analysis
The average 2018 MERCEDES S-CLASS has 75,456 miles on the clock, which is well above the expected 44,400 miles for a 6-year-old car. Check service history carefully, as high-mileage cars need consistent maintenance to stay reliable.
Best year to buy a MERCEDES S-CLASS?
The most reliable year is the 2020 model with a 95% MOT pass rate, while the 1992 model has the lowest at 72%. The 2018 sits between the two at 94%.
How much does a 2018 MERCEDES S-CLASS cost to run?
Based on 7,400 miles/year (UK average), current fuel prices, and repair likelihood from MOT pass rate data. Insurance not included.
MERCEDES S-CLASS by Year
| Year | Pass Rate | Tests | Avg Mileage |
|---|---|---|---|
| 2021 | 91% | 164 | 32,036 mi |
| 2020 | 95% | 540 | 43,972 mi |
| 2019 | 94% | 5,921 | 67,860 mi |
| 2018 | 94% | 6,518 | 75,456 mi |
| 2017 | 93% | 5,990 | 73,988 mi |
| 2016 | 91% | 6,819 | 74,260 mi |
| 2015 | 92% | 5,513 | 87,325 mi |
| 2014 | 92% | 3,915 | 95,545 mi |
| 2013 | 89% | 2,145 | 108,065 mi |
| 2012 | 88% | 2,817 | 100,420 mi |
| 2011 | 87% | 2,202 | 117,628 mi |
| 2010 | 85% | 2,001 | 110,934 mi |
| 2009 | 82% | 1,990 | 114,274 mi |
| 2008 | 84% | 2,232 | 110,584 mi |
| 2007 | 84% | 2,940 | 117,418 mi |
| 2006 | 87% | 2,334 | 111,043 mi |
| 2005 | 84% | 1,301 | 132,014 mi |
| 2004 | 82% | 1,158 | 124,020 mi |
| 2003 | 82% | 1,227 | 120,882 mi |
| 2002 | 79% | 720 | 115,052 mi |
| 2001 | 79% | 735 | 107,381 mi |
| 2000 | 81% | 562 | 102,703 mi |
| 1999 | 78% | 434 | 98,447 mi |
| 1998 | 81% | 522 | 111,371 mi |
| 1997 | 86% | 373 | 107,182 mi |
| 1996 | 83% | 348 | 109,185 mi |
| 1995 | 86% | 286 | 111,087 mi |
| 1994 | 92% | 140 | 106,787 mi |
| 1993 | 76% | 49 | 112,335 mi |
| 1992 | 72% | 121 | 119,350 mi |
| 1991 | 92% | 118 | 120,508 mi |
| 1990 | 87% | 125 | 142,121 mi |
Checking a specific MERCEDES S-CLASS?
Enter the reg plate to see its individual MOT history, mileage verification, and predicted costs.
About the 2018 MERCEDES S-CLASS
The 2018 MERCEDES S-CLASS is a large car with a 2625cc petrol engine. 6,518 of these vehicles were MOT tested in 2024, making it a reasonably common sight on UK roads. It ranks in the top 20% of all 2018 cars for reliability.
With an average of 75,456 miles at 6 years old, MERCEDES S-CLASS owners cover more miles than the average driver. High-mileage examples should be checked carefully for wear on suspension, brakes, and drivetrain components.
2018 MERCEDES S-CLASS Fuel Costs
The 2625cc petrol engine is on the larger side, so fuel won't be this car's strong point. Expect around 30 mpg in mixed driving, which works out to roughly £1,592 per year at current petrol prices of 142p per litre (based on 7,400 miles per year).
What does it cost to own a 2018 MERCEDES S-CLASS?
Total estimated annual running cost is £2,037 (£170/month), broken down as £1592 fuel, £190 road tax, £55 MOT, and £200 predicted repairs. The low repair estimate reflects the excellent 94% pass rate. These cars rarely fail their MOT, so unexpected bills are less likely.
MERCEDES S-CLASS Reliability Trend
Newer MERCEDES S-CLASSs show better MOT pass rates than older ones, with an average improvement of 6 percentage points.
Buying a Used 2018 MERCEDES S-CLASS
At 6 years old, the MERCEDES S-CLASS offers good value with plenty of life remaining. Most manufacturer warranties will have expired, so a pre-purchase inspection is worth the cost. If you're flexible on year, the 2020 model has the highest pass rate at 95%. With 6,518 MOT tests in our data, there's strong statistical confidence in these figures.
Alternatives to the 2018 MERCEDES S-CLASS
The MERCEDES S-CLASS is actually the most reliable option among similar petrol large cars from this era. Here are comparable petrol cars with similar engines:
- BMW 5 SERIES (2018) 91% pass rate (-3%) from 40,272 tests
- LAND ROVER RANGE ROVER SPORT (2018) 93% pass rate (-1%) from 34,257 tests
- BMW X3 (2019) 92% pass rate (-2%) from 32,937 tests
- MERCEDES GLC (2019) 93% pass rate (-1%) from 30,341 tests