AUDI A4 S LINE 30 TDI MHEV S-A (2021)
Running costs, reliability data, and common problems from 95 real MOT tests.
Annual Cost
£1,487
£124/month
MOT Pass Rate
92%
Excellent
Road Tax
£195
Flat rate/year
Insurance
Grp 18-32
1968cc Diesel
Great Choice
92% pass rate, £1487/year to run. 10 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 10 points above the national average of 82%.
At 5 years old, 92% of AUDI A4 S LINE 30 TDI MHEV S-As from 2021 passed their MOT first time in 2026. That's based on 95 tests across the UK. The average mileage at this age is 49,061 miles.
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How Does It Compare?
Mileage Analysis
49,061
Average miles
37,000
Expected for age
The average 2021 AUDI A4 S LINE 30 TDI MHEV S-A has 49,061 miles on the clock, which is above the expected 37,000 miles for a 5-year-old car. Higher-mileage cars often have more motorway miles, which is generally less harmful than stop-start urban driving.
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About the 2021 AUDI A4 S LINE 30 TDI MHEV S-A
The 2021 AUDI A4 S LINE 30 TDI MHEV S-A is a premium with a 1968cc diesel engine. 95 of these vehicles were MOT tested in 2026, making it a rare model on UK roads. Among all cars from 2021, the average MOT pass rate is 92%, and this model falls short of that benchmark.
With an average of 49,061 miles at 5 years old, AUDI A4 S LINE 30 TDI MHEV S-A owners cover more miles than the average driver.
2021 AUDI A4 S LINE 30 TDI MHEV S-A Fuel Costs
The 1968cc 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 AUDI A4 S LINE 30 TDI MHEV S-A?
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 92% pass rate. These cars rarely fail their MOT, so unexpected bills are less likely.
Buying a Used 2021 AUDI A4 S LINE 30 TDI MHEV S-A
At 5 years old, the AUDI A4 S LINE 30 TDI MHEV S-A 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 95 tests in our data, these figures should be treated as indicative rather than definitive.
Common Issues to Watch For
Based on the 2021 AUDI A4 S LINE 30 TDI MHEV S-A'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 AUDI A4 S LINE 30 TDI MHEV S-A stacks up against similar cars for annual running costs, insurance, and tax.
| Car | Pass Rate | Fuel/yr | Tax/yr | Insurance | Total/yr |
|---|---|---|---|---|---|
| AUDI A4 S LINE 30 TDI MHEV S-A(2021) | 92% | £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 Audi Models
Explore other Audi cars or similar models in the same category.
AUDI A3
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AUDI A1
2016 · 1395cc Petrol
AUDI A4
2017 · 1968cc Diesel
FORD FOCUS
2019 · 1499cc Diesel
FORD KUGA
2019 · 1997cc Diesel
VOLKSWAGEN POLO
2019 · 1598cc Diesel
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