Is the 2021 AUDI A8 reliable?

Excellent reliability. Very few MOT failures. 98% of AUDI A8s from 2021 passed their MOT first time in 2026, based on 170 tests. That's 16 points above the national average of 82%.

How much does a 2021 AUDI A8 cost to run?

Estimated annual running cost is £1,695 (£141/month), including £1245 fuel, £195 road tax, £55 MOT, and £200 predicted repairs.

What is the MOT pass rate for a 2021 AUDI A8?

The 2021 AUDI A8 has a 98% MOT pass rate based on 170 tests in 2026. This ranks 207 out of 3373 cars from 2021.

Which year AUDI A8 is most reliable?

The 2021 AUDI A8 has the highest MOT pass rate at 98%. The least reliable year is 2000 at 77%.

What is the average mileage for a 2021 AUDI A8?

The average mileage for a 2021 AUDI A8 is 35,071 miles, which is in line with the expected 37,000 miles for a 5-year-old car, suggesting normal everyday use.

AUDI A8 (2021)

Running costs, reliability data, and common problems from 170 real MOT tests.

Annual Cost

£1,695

£141/month

MOT Pass Rate

98%

Excellent

Road Tax

£195

Flat rate/year

Insurance

Grp 30-42

2967cc Diesel

Great Choice

98% pass rate, £1695/year to run. 16 points above average.

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Diesel2967cc5 years old170 tests35k miles avg

Annual Running Costs

Fuel (Diesel, 2967cc)

~40 mpg

£1,245

Road Tax

Flat rate (post-2017)

£195

MOT Test

£55

Predicted Repairs

Low estimate due to excellent reliability

£200

Total per year£1,695

Per month£141/mo

Per week£33/wk

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

98% MOT pass rate(Excellent)

0%National avg: 82%100%

Excellent reliability. Very few MOT failures. That's 16 points above the national average of 82%. It also outperforms the AUDI brand average of 90%.

At 5 years old, 98% of AUDI A8s from 2021 passed their MOT first time in 2026. That's based on 170 tests across the UK. The average mileage at this age is 35,071 miles.

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How Does It Compare?

Rank among 2021 cars207th of 3,373(top 6%)

Rank among AUDI models60th of 1,079(top 6%)

vs national average+16%(82% avg)

vs 2021 cars average+6%(92% avg)

vs AUDI average+8%(90% avg)

Mileage Analysis

35,071

Average miles

37,000

Expected for age

The average 2021 AUDI A8 has 35,071 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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AUDI A8 by Year

Year	Pass Rate	Tests	Avg Mileage
2021	98%	170	35,071 mi
2020	96%	599	39,317 mi
2019	95%	1,932	50,413 mi
2018	95%	2,387	59,736 mi
2017	95%	1,392	72,207 mi
2016	94%	1,876	80,025 mi
2015	93%	2,300	85,475 mi
2014	94%	1,889	98,201 mi
2013	91%	1,562	108,280 mi
2012	92%	1,468	113,405 mi
2011	93%	1,392	120,960 mi
2010	87%	933	124,272 mi
2009	89%	735	138,957 mi
2008	87%	1,332	140,305 mi
2007	86%	1,124	147,303 mi
2006	85%	748	146,966 mi
2005	87%	661	142,434 mi
2004	80%	349	134,086 mi
2003	84%	223	134,224 mi
2002	84%	166	137,356 mi
2001	85%	157	141,044 mi
2000	77%	104	143,697 mi
1999	80%	192	140,354 mi
1998	80%	122	136,028 mi
1997	79%	115	131,393 mi
1996	74%	31	135,336 mi

Similar Cars to Consider

MERCEDES E

2019 · 2925cc Diesel

£1,690/year

90%

-8%

FORD RANGER

2019 · 3198cc Diesel

£1,840/year

87%

-11%

AUDI Q5

2019 · 2967cc Diesel

£1,690/year

93%

-5%

AUDI A5

2019 · 2967cc Diesel

£1,690/year

90%

-8%

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About the 2021 AUDI A8

The 2021 AUDI A8 is a premium performance with a 2967cc diesel engine. 170 of these vehicles were MOT tested in 2026, making it a rare model on UK roads. It ranks in the top 6% of all 2021 cars for reliability.

With an average of 35,071 miles at 5 years old, AUDI A8 owners drive about as much as the UK average.

2021 AUDI A8 Fuel Costs

The 2967cc diesel engine is on the larger side, so fuel won't be this car's strong point. Expect around 40 mpg in mixed driving, which works out to roughly £1,245 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 A8?

Total estimated annual running cost is £1,695 (£141/month), broken down as £1245 fuel, £195 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.

AUDI A8 Reliability Trend

Newer AUDI A8s show better MOT pass rates than older ones, with an average improvement of 10 percentage points.

Buying a Used 2021 AUDI A8

At 5 years old, the AUDI A8 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 AUDI A8's fuel type, age, and engine size, these are the most likely problem areas to check.

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.

Dual Mass Flywheel

Medium risk

Larger diesel engines put extra strain on the dual mass flywheel. Listen for rattling at idle. Replacement with clutch is £800-£1,500.

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 A8 stacks up against similar cars for annual running costs, insurance, and tax.

Car	Pass Rate	Fuel/yr	Tax/yr	Insurance	Total/yr
AUDI A8(2021)	98%	£1245	£195	Grp 30-42	£1695
MERCEDES E(2019)	90%	£1245	£190	Grp 30-42	£1690-£5
FORD RANGER(2019)	87%	£1245	£190	Grp 35-50	£1840+£145
AUDI Q5(2019)	93%	£1245	£190	Grp 30-42	£1690-£5
AUDI A5(2019)	90%	£1245	£190	Grp 30-42	£1690-£5

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.