Audi A3 S Line 30 TDI (2021)

Estimated running costs and MOT pass rates from 470 MOT tests in 2024.

Annual Cost

£2,002

£167/month

MOT Pass Rate

89%

Good

Road Tax

£200

Standard rate/year

Est. Insurance

Grp 18-32

1968cc Diesel

Solid Option

89% pass rate, £2,002/year to run. 7 points above average.

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Diesel1968cc5 years old470 tests39k miles avg

Annual Running Costs

Fuel (Diesel, 1968cc)

~48 mpg

£1,397

Road Tax

Standard rate (from April 2017)

£200

MOT Test

£55

Predicted Repairs

£350

Total per year£2,002

Per month£167/mo

Per week£39/wk

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

89% MOT pass rate(Good)

0%All-model avg: 82%100%

Good reliability. Occasional issues but generally solid. That's 7 points above the average of 82% across all models in our data.

89% of MOT tests on Audi A3 S Line 30 TDIs from 2021 ended in a pass in 2024, when they were about 3 years old. That's based on 470 tests across the UK, retests included. The average mileage recorded at those tests was 39,098 miles.

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How Does It Compare?

Rank among 2021 models2664th of 3,336(bottom 21%)

Rank among Audi models739th of 1,066(bottom half)

vs average of all models+7%(82% avg)

vs 2021 models average-3%(92% avg)

vs Audi average-1%(90% avg)

Mileage Analysis

39,098

Average miles

22,200

Expected for age

The average 2021 Audi A3 S Line 30 TDI had 39,098 miles on the clock at its 2024 MOT, which is well above the expected 22,200 miles for a 3-year-old car. Check service history carefully, as high-mileage cars need consistent maintenance to stay reliable.

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Best Year to Buy?

Of the years with at least 100 tests, the 2020 model has the highest MOT pass rate at 92%, while the 2021 model has the lowest at 89%. Consider a different year if reliability is a priority. Newer cars usually pass more often simply because they are younger, so compare years of a similar age.

Audi A3 S Line 30 TDI by Year

Year	Pass Rate	Tests	Avg Mileage
2021	89%	470	39,098 mi
2020	92%	219	45,665 mi

Similar Cars to Consider

Ford Focus

2019 · 1499cc Diesel

£1,824/year

89%

same

Ford Kuga

2019 · 1997cc Diesel

£1,852/year

91%

+2%

Volkswagen Polo

2019 · 1598cc Diesel

£1,824/year

89%

same

Kia Sportage

2019 · 1598cc Diesel

£1,824/year

89%

same

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About the 2021 Audi A3 S Line 30 TDI

The 2021 Audi A3 S Line 30 TDI is a premium car. Our records list a 1968cc diesel engine, though engines vary between versions. 470 MOT tests were recorded on this model in 2024, making it a less common model in the UK market. It sits in the bottom 21% of 2021 models for MOT pass rate.

With an average of 39,098 miles recorded at its 2024 MOT tests, Audi A3 S Line 30 TDI owners cover more miles than the average driver. High-mileage examples should be checked carefully for wear on suspension, brakes, and drivetrain components.

2021 Audi A3 S Line 30 TDI 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 £1,397 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 2021 Audi A3 S Line 30 TDI?

Total estimated annual running cost is £2,002 (£167/month), broken down as £1,397 fuel, £200 road tax, £55 MOT, and £350 predicted repairs. Repair costs are moderate, reflecting the 89% pass rate. Keeping on top of servicing will help avoid surprises.

Buying a Used 2021 Audi A3 S Line 30 TDI

At 5 years old, the Audi A3 S Line 30 TDI 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

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 out

Short journeys clog the DPF. Replacement costs £1,000-£2,500. Check the DPF warning light and ask about driving patterns.

Turbo Wear

Medium risk

Diesel turbos work harder and wear faster. Listen for whining noises and check for oil leaks around the turbo housing.

AdBlue System

Medium risk

Post-2015 diesels use AdBlue for emissions. Sensor failures and tank heater issues are common. Budget £200-£500 for repairs.

EGR Valve

Low risk

Exhaust Gas Recirculation valves clog with carbon deposits, causing rough running and poor economy. Cleaning costs £150-£300, replacement £300-£600.

Service History

Low risk

Always 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 A3 S Line 30 TDI 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
Audi A3 S Line 30 TDI(2021)	89%	£1,397	£200	Grp 18-32	£2,002
Ford Focus(2019)	89%	£1,219	£200	Grp 12-25	£1,824-£178
Ford Kuga(2019)	91%	£1,397	£200	Grp 18-32	£1,852-£150
Volkswagen Polo(2019)	89%	£1,219	£200	Grp 12-25	£1,824-£178
Kia Sportage(2019)	89%	£1,219	£200	Grp 12-25	£1,824-£178

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 2021 Audi A3 S Line 30 TDI

Is the 2021 Audi A3 S Line 30 TDI reliable?

Good reliability. Occasional issues but generally solid. 89% of MOT tests on 2021 Audi A3 S Line 30 TDIs ended in a pass, from 470 tests (DVSA MOT data for tests in 2024, retests included). That's 7 points above the average of 82% across all models in the same data.

How much does a 2021 Audi A3 S Line 30 TDI cost to run?

Our estimate is £2,002 a year (£167 a month): £1,397 fuel, £200 road tax, £55 MOT and £350 predicted repairs, based on 7,400 miles a year. Insurance is not included.

What is the MOT pass rate for a 2021 Audi A3 S Line 30 TDI?

89% of 470 MOT tests on the 2021 Audi A3 S Line 30 TDI ended in a pass (DVSA MOT data for tests in 2024, retests included). That ranks it 2664th of 3,336 models first registered in 2021 (bottom 21%).

Which year Audi A3 S Line 30 TDI has the best MOT pass rate?

Of the years with at least 100 tests, the 2020 Audi A3 S Line 30 TDI has the highest MOT pass rate at 92% and the 2021 the lowest at 89%. Newer cars usually pass more often simply because they are younger and have done fewer miles.

What is the average mileage for a 2021 Audi A3 S Line 30 TDI?

The average mileage recorded at MOT tests on the 2021 Audi A3 S Line 30 TDI is 39,098 miles, which is well above the expected 22,200 miles for a 3-year-old car. Check service history carefully, as high-mileage cars need consistent maintenance to stay reliable.