BMW 420 (2021)
Running costs, reliability data, and common problems from 730 real MOT tests.
Annual Cost
£1,487
£124/month
MOT Pass Rate
94%
Excellent
Road Tax
£195
Flat rate/year
Insurance
Grp 18-32
1995cc Diesel
Great Choice
94% pass rate, £1487/year to run. 12 points above average.
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Annual Running Costs
~48 mpg
Flat rate (post-2017)
Low estimate due to excellent reliability
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
Excellent reliability. Very few MOT failures. That's 12 points above the national average of 82%. It also outperforms the BMW brand average of 88%.
At 5 years old, 94% of BMW 420s from 2021 passed their MOT first time in 2026. That's based on 730 tests across the UK. The average mileage at this age is 28,172 miles.
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How Does It Compare?
Mileage Analysis
28,172
Average miles
37,000
Expected for age
The average 2021 BMW 420 has 28,172 miles on the clock, which is below the expected 37,000 miles for a 5-year-old car. This suggests lighter use than average, which generally means less wear on major components.
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BMW 420 by Year
Similar Cars to Consider
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About the 2021 BMW 420
The 2021 BMW 420 is a premium with a 1995cc diesel engine. 730 of these vehicles were MOT tested in 2026, making it a less common model in the UK market. Among all cars from 2021, the average MOT pass rate is 92%, and this model beats that benchmark.
With an average of 28,172 miles at 5 years old, BMW 420 owners tend to use this car less than the typical driver.
2021 BMW 420 Fuel Costs
The 1995cc 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 BMW 420?
Total estimated annual running cost is £1,487 (£124/month), broken down as £1037 fuel, £195 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.
BMW 420 Reliability Trend
Newer BMW 420s show better MOT pass rates than older ones, with an average improvement of 4 percentage points.
Buying a Used 2021 BMW 420
At 5 years old, the BMW 420 offers good value with plenty of life remaining. Most manufacturer warranties will have expired, so a pre-purchase inspection is worth the cost.
Common Issues to Watch For
Based on the 2021 BMW 420'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 BMW 420 stacks up against similar cars for annual running costs, insurance, and tax.
| Car | Pass Rate | Fuel/yr | Tax/yr | Insurance | Total/yr |
|---|---|---|---|---|---|
| BMW 420(2021) | 94% | £1037 | £195 | Grp 18-32 | £1487 |
| FORD FOCUS(2019) | 89% | £905 | £190 | Grp 12-25 | £1500+£13 |
| FORD KUGA(2019) | 91% | £1037 | £190 | Grp 18-32 | £1482-£5 |
| VOLKSWAGEN POLO(2019) | 89% | £905 | £190 | Grp 12-25 | £1500+£13 |
| FORD TRANSIT CUSTOM(2019) | 87% | £1037 | £190 | Grp 18-32 | £1632+£145 |
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 Bmw Models
Explore other Bmw cars or similar models in the same category.
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FORD FOCUS
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2019 · 1997cc Diesel
VOLKSWAGEN POLO
2019 · 1598cc Diesel
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