Mercedes M8 (2018)
Estimated running costs and MOT pass rates from 111 MOT tests in 2024.
Annual Cost
£2,431
£203/month
MOT Pass Rate
79%
Average
Road Tax
£200
Standard rate/year
Est. Insurance
Grp 25-38
2143cc Diesel
Check Carefully
79% pass rate, £2,431/year to run. Close to the average across all models.
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Annual Running Costs
~40 mpg
Standard rate (from April 2017)
Estimates based on 7,400 miles/year (UK average), diesel at 199.33p a litre (GOV.UK weekly average, week of 19 October 2026), GOV.UK road tax rates and repair likelihood from MOT data. Insurance not included. Cars registered from April 2017 pay the £200 standard rate, plus £440 a year for five years (from the second year) if they cost over £40,000 new (over £50,000 for electric cars).
Reliability Verdict
Average reliability. Expect some repairs as it ages. That's close to the average of 82% across all models in our data. It falls below the Mercedes brand average of 87%.
79% of MOT tests on Mercedes M8s from 2018 ended in a pass in 2024, when they were about 6 years old. That's based on 111 tests across the UK, retests included. The average mileage recorded at those tests was 198,084 miles.
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How Does It Compare?
Mileage Analysis
198,084
Average miles
44,400
Expected for age
The average 2018 Mercedes M8 had 198,084 miles on the clock at its 2024 MOT, 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.
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Mercedes M8 by Year
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About the 2018 Mercedes M8
The 2018 Mercedes M8 is a premium car. Our records list a 2143cc diesel engine, though engines vary between versions. 111 MOT tests were recorded on this model in 2024, making it a rare model on UK roads. It sits in the bottom 5% of 2018 models for MOT pass rate.
With an average of 198,084 miles recorded at its 2024 MOT tests, Mercedes M8 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 M8 Fuel Costs
The 2143cc diesel engine offers a reasonable balance between performance and economy. Expect around 40 mpg in mixed driving, which works out to roughly £1,676 per year with diesel at 199.33p per litre (GOV.UK weekly average, week of 19 October 2026; based on 7,400 miles per year). Diesel cars of this age should have their DPF (diesel particulate filter) checked, as replacements can be costly.
What does it cost to own a 2018 Mercedes M8?
Total estimated annual running cost is £2,431 (£203/month), broken down as £1,676 fuel, £200 road tax, £55 MOT, and £500 predicted repairs. Repair costs are moderate, reflecting the 79% pass rate. Keeping on top of servicing will help avoid surprises.
Buying a Used 2018 Mercedes M8
At 8 years old, this is a solid used buy if you find one with good service history. Depreciation has levelled off, so you won't lose much more value. Focus on condition over mileage.
Common Issues to Watch For
These are typical issues for cars of this age, fuel type and engine size, not faults recorded on this model's MOT tests. Use them as a checklist when you view one.
DPF (Diesel Particulate Filter)
Watch outShort journeys clog the DPF. Replacement costs £1,000-£2,500. Check the DPF warning light and ask about driving patterns.
Turbo Wear
Watch outDiesel turbos work harder and wear faster. Listen for whining noises and check for oil leaks around the turbo housing.
AdBlue System
Medium riskPost-2015 diesels use AdBlue for emissions. Sensor failures and tank heater issues are common. Budget £200-£500 for repairs.
EGR Valve
Watch outExhaust Gas Recirculation valves clog with carbon deposits, causing rough running and poor economy. Cleaning costs £150-£300, replacement £300-£600.
Dual Mass Flywheel
Watch outLarger diesel engines put extra strain on the dual mass flywheel. Listen for rattling at idle. Replacement with clutch is £800-£1,500.
Suspension Wear
Medium riskShock absorbers, springs, and anti-roll bar links typically need attention around this age. Listen for clunks over bumps and check for uneven tyre wear.
Clutch Wear
Watch outWith an average of 198k miles, clutch replacement may be due (typical lifespan 60,000-100,000 miles). Budget £400-£800 for a new clutch kit.
Brake Discs and Pads
Medium riskHigh-mileage cars often need brake disc replacement, not just pads. A full set of discs and pads costs £200-£500 per axle.
Engine Mounts
Medium riskWorn engine mounts cause excessive vibration and movement. Replacement costs £150-£400 per mount. Check for vibration at idle with the bonnet open.
Service History
Low riskAlways request a full service history. Regular servicing is the single best indicator of how well a car has been maintained, regardless of mileage.
Running Costs Compared
How the 2018 Mercedes M8 stacks up against similar cars for estimated annual running costs, insurance group, and tax.
| Car | Pass Rate | Fuel/yr | Tax/yr | Est. Ins. Group | Total/yr |
|---|---|---|---|---|---|
| Mercedes M8(2018) | 79% | £1,676 | £200 | Grp 25-38 | £2,431 |
| Volkswagen Golf(2018) | 92% | £1,397 | £200 | Grp 18-32 | £1,852-£579 |
| Ford Kuga(2019) | 91% | £1,397 | £200 | Grp 18-32 | £1,852-£579 |
| Kia Sportage(2016) | 85% | £1,397 | £275 | Grp 18-32 | £2,077-£354 |
| Land Rover Range Rover Evoque(2016) | 90% | £1,397 | £275 | Grp 18-32 | £1,927-£504 |
Estimates based on 7,400 miles/year, GOV.UK average pump prices for the week of 19 October 2026, GOV.UK road tax rates and MOT data. Insurance groups are our rough estimate from engine size, not official groups. Actual costs vary by driver, location, and usage.
Questions about the 2018 Mercedes M8
Is the 2018 Mercedes M8 reliable?
Average reliability. Expect some repairs as it ages. 79% of MOT tests on 2018 Mercedes M8s ended in a pass, from 111 tests (DVSA MOT data for tests in 2024, retests included). That's 3 points below the average of 82% across all models in the same data.
How much does a 2018 Mercedes M8 cost to run?
Our estimate is £2,431 a year (£203 a month): £1,676 fuel, £200 road tax, £55 MOT and £500 predicted repairs, based on 7,400 miles a year. Insurance is not included.
What is the MOT pass rate for a 2018 Mercedes M8?
79% of 111 MOT tests on the 2018 Mercedes M8 ended in a pass (DVSA MOT data for tests in 2024, retests included). That ranks it 583rd of 607 models first registered in 2018 (bottom 5%).
Which year Mercedes M8 has the best MOT pass rate?
Of the years with at least 100 tests, the 2018 Mercedes M8 has the highest MOT pass rate at 79% and the 2017 the lowest at 76%. Newer cars usually pass more often simply because they are younger and have done fewer miles.
What is the average mileage for a 2018 Mercedes M8?
The average mileage recorded at MOT tests on the 2018 Mercedes M8 is 198,084 miles, 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.
Related Mercedes Models
Explore other Mercedes cars or similar models in the same category.
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Volkswagen Golf
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Ford Kuga
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Kia Sportage
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