Mercedes G (2018)
Estimated running costs and MOT pass rates from 109 MOT tests in 2024.
Annual Cost
£2,413
£201/month
MOT Pass Rate
98%
Excellent
Road Tax
£200
Standard rate/year
Est. Insurance
Grp 35-50
3982cc Petrol
Great Choice
98% pass rate, £2,413/year to run. 16 points above average.
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Annual Running Costs
~30 mpg
Standard rate (from April 2017)
Low estimate due to excellent reliability
Estimates based on 7,400 miles/year (UK average), petrol at 174.57p 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
Excellent reliability. Very few MOT failures. That's 16 points above the average of 82% across all models in our data. It also outperforms the Mercedes brand average of 87%.
98% of MOT tests on Mercedes Gs from 2018 ended in a pass in 2024, when they were about 6 years old. That's based on 109 tests across the UK, retests included. The average mileage recorded at those tests was 33,847 miles.
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How Does It Compare?
Mileage Analysis
33,847
Average miles
44,400
Expected for age
The average 2018 Mercedes G had 33,847 miles on the clock at its 2024 MOT, which is below the expected 44,400 miles for a 6-year-old car. This suggests lighter use than average, which generally means less wear on major components.
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Mercedes G by Year
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About the 2018 Mercedes G
The 2018 Mercedes G is a premium performance car. Our records list a 3982cc petrol engine, though engines vary between versions. 109 MOT tests were recorded on this model in 2024, making it a rare model on UK roads. It ranks in the top 7% of all 2018 models for MOT pass rate.
With an average of 33,847 miles recorded at its 2024 MOT tests, Mercedes G owners tend to use this car less than the typical driver.
2018 Mercedes G Fuel Costs
The 3982cc 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 £1,958 per year with petrol at 174.57p per litre (GOV.UK weekly average, week of 19 October 2026; based on 7,400 miles per year).
What does it cost to own a 2018 Mercedes G?
Total estimated annual running cost is £2,413 (£201/month), broken down as £1,958 fuel, £200 road tax, £55 MOT, and £200 predicted repairs. The low repair estimate reflects the excellent 98% pass rate. These cars rarely fail their MOT, so unexpected bills are less likely.
Mercedes G Reliability Trend
The Mercedes G has maintained consistent MOT pass rates across model years, varying by only 1 percentage point.
Buying a Used 2018 Mercedes G
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.
Timing Chain / Belt
Watch outAt 8 years old, check whether the timing belt has been replaced (typically due every 5-7 years or 60,000-100,000 miles). A snapped belt can destroy the engine.
Oil Consumption
Medium riskLarger petrol engines can develop higher oil consumption as they age. Check the oil level and look for blue smoke from the exhaust.
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.
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 G 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 G(2018) | 98% | £1,958 | £200 | Grp 35-50 | £2,413 |
| Mercedes C(2016) | 88% | £1,958 | £790 | Grp 35-50 | £3,153+£740 |
| Audi A6(2016) | 89% | £1,958 | £790 | Grp 35-50 | £3,153+£740 |
| Porsche Cayenne(2019) | 95% | £1,958 | £200 | Grp 35-50 | £2,413same |
| Porsche 911(2018) | 96% | £1,958 | £200 | Grp 35-50 | £2,413same |
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 G
Is the 2018 Mercedes G reliable?
Excellent reliability. Very few MOT failures. 98% of MOT tests on 2018 Mercedes Gs ended in a pass, from 109 tests (DVSA MOT data for tests in 2024, retests included). That's 16 points above the average of 82% across all models in the same data.
How much does a 2018 Mercedes G cost to run?
Our estimate is £2,413 a year (£201 a month): £1,958 fuel, £200 road tax, £55 MOT and £200 predicted repairs, based on 7,400 miles a year. Insurance is not included.
What is the MOT pass rate for a 2018 Mercedes G?
98% of 109 MOT tests on the 2018 Mercedes G ended in a pass (DVSA MOT data for tests in 2024, retests included). That ranks it 37th of 607 models first registered in 2018 (top 7%).
Which year Mercedes G has the best MOT pass rate?
Of the years with at least 100 tests, the 2018 Mercedes G has the highest MOT pass rate at 98% and the 2019 the lowest at 93%. 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 G?
The average mileage recorded at MOT tests on the 2018 Mercedes G is 33,847 miles, which is below the expected 44,400 miles for a 6-year-old car. This suggests lighter use than average, which generally means less wear on major components.
Related Mercedes Models
Explore other Mercedes cars or similar models in the same category.
Mercedes A
2019 · 1461cc Diesel
Mercedes C
2017 · 1991cc Hybrid
Mercedes A-Class
2017 · 1461cc Diesel
Mercedes C
2016 · 3982cc Petrol
Audi A6
2016 · 3993cc Petrol
Porsche Cayenne
2019 · 3996cc Petrol
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