MERCEDES G-CLASS (2021)
Running costs, reliability data, and common problems from 65 real MOT tests.
Annual Cost
£1,787
£149/month
MOT Pass Rate
78%
Average
Road Tax
£195
Flat rate/year
Insurance
Grp 18-32
1950cc Diesel
Check Carefully
78% pass rate, £1787/year to run. Close to the national average.
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Annual Running Costs
~48 mpg
Flat rate (post-2017)
Based on 7,400 miles/year (UK average), current fuel prices, and repair likelihood from MOT data. Insurance not included.
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Reliability Verdict
Average reliability. Expect some repairs as it ages. That's close to the national average of 82%. It falls below the MERCEDES brand average of 87%.
At 5 years old, 78% of MERCEDES G-CLASSs from 2021 passed their MOT first time in 2026. That's based on 65 tests across the UK. The average mileage at this age is 30,190 miles.
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How Does It Compare?
Mileage Analysis
30,190
Average miles
37,000
Expected for age
The average 2021 MERCEDES G-CLASS has 30,190 miles on the clock, which is in line with the expected 37,000 miles for a 5-year-old car, suggesting normal everyday use.
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Best Year to Buy?
The most reliable year is the 2020 model with a 98% MOT pass rate, while the 2021 model has the lowest at 78%. Consider a different year if reliability is a priority.
MERCEDES G-CLASS by Year
| Year | Pass Rate | Tests | Avg Mileage | |
|---|---|---|---|---|
| 2021 | 78% | 65 | 30,190 mi | |
| 2020 | 98% | 66 | 32,570 mi | |
| 2019 | 96% | 319 | 41,698 mi | |
| 2018 | 94% | 807 | 39,199 mi | |
| 2017 | 86% | 691 | 43,730 mi | |
| 2016 | 94% | 604 | 58,012 mi | |
| 2015 | 88% | 591 | 48,991 mi | |
| 2014 | 92% | 362 | 54,969 mi | |
| 2013 | 94% | 449 | 69,675 mi | |
| 2012 | 90% | 221 | 76,209 mi | |
| 2011 | 96% | 92 | 70,666 mi | |
| 2010 | 73% | 33 | 78,145 mi | |
| 2007 | 100% | 35 | 103,461 mi | |
| 2001 | 60% | 42 | 93,234 mi | |
| 1999 | 82% | 44 | 113,541 mi |
Similar Cars to Consider
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About the 2021 MERCEDES G-CLASS
The 2021 MERCEDES G-CLASS is a family car with a 1950cc diesel engine. 65 of these vehicles were MOT tested in 2026, making it a rare model on UK roads. It sits in the bottom 99% of 2021 cars for MOT pass rates.
With an average of 30,190 miles at 5 years old, MERCEDES G-CLASS owners drive about as much as the UK average.
2021 MERCEDES G-CLASS Fuel Costs
The 1950cc diesel engine offers a reasonable balance between performance and economy. Expect around 48 mpg in mixed driving, which works out to roughly £1,037 per year at current diesel prices of 148p per litre (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 2021 MERCEDES G-CLASS?
Total estimated annual running cost is £1,787 (£149/month), broken down as £1037 fuel, £195 road tax, £55 MOT, and £500 predicted repairs. Repair costs are moderate, reflecting the 78% pass rate. Keeping on top of servicing will help avoid surprises.
MERCEDES G-CLASS Reliability Trend
The MERCEDES G-CLASS has maintained consistent MOT pass rates across model years, varying by only 1 percentage points.
Buying a Used 2021 MERCEDES G-CLASS
At 5 years old, the MERCEDES G-CLASS offers good value with plenty of life remaining. Most manufacturer warranties will have expired, so a pre-purchase inspection is worth the cost. Note: with only 65 tests in our data, these figures should be treated as indicative rather than definitive.
Common Issues to Watch For
Based on the 2021 MERCEDES G-CLASS's fuel type, age, and engine size, these are the most likely problem areas to check.
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
Medium riskDiesel 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
Low riskExhaust Gas Recirculation valves clog with carbon deposits, causing rough running and poor economy. Cleaning costs £150-£300, replacement £300-£600.
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 2021 MERCEDES G-CLASS stacks up against similar cars for annual running costs, insurance, and tax.
| Car | Pass Rate | Fuel/yr | Tax/yr | Insurance | Total/yr |
|---|---|---|---|---|---|
| MERCEDES G-CLASS(2021) | 78% | £1037 | £195 | Grp 18-32 | £1787 |
| FORD FOCUS(2019) | 89% | £905 | £190 | Grp 12-25 | £1500-£287 |
| MERCEDES A(2019) | 91% | £905 | £190 | Grp 12-25 | £1350-£437 |
| FORD KUGA(2019) | 91% | £1037 | £190 | Grp 18-32 | £1482-£305 |
| VOLKSWAGEN POLO(2019) | 89% | £905 | £190 | Grp 12-25 | £1500-£287 |
Estimates based on 7,400 miles/year, current fuel prices, and MOT data. Insurance groups are indicative. Actual costs vary by driver, location, and usage.
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
FORD FOCUS
2019 · 1499cc Diesel
MERCEDES A
2019 · 1461cc Diesel
FORD KUGA
2019 · 1997cc Diesel
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