Audi A6 2020: reliability & common MOT faults

At a glance

How 3,222 first tests went in 2025.

Passed first time: 90 in every 100
Did not pass first time: 10 in every 100325 failed first-attempt tests
The typical car: 5 yearsabout 48,902 miles
First tests counted: 3,222

What failed most often

Tyre condition (rear)16 in every 100 failed tests

How we count this. Data: UK MOT open data, 2025. Only Class 4 cars on their first MOT of the year are counted. A car that fails and is fixed at the test station still counts as a fail in the first-attempt rate. These are raw results, not adjusted for age, mileage, or peer mix. The MOT does not test engine or gearbox internals.

Note:

These are patterns across 2020 Audi A6 vehicles in 2025, not a prediction that any one car will have them. Faults are grouped by part of the car. A wear pattern follows age and use more than the way the car was built. They come from MOT defect codes, not manufacturer bulletins, recalls or a diagnosis of any one car.

Tyres

One wear pattern: tyre tread depth (rear), 2.6 times as often as on similar cars.

Figures below are measured across the 325 failed first attempts in 2025 that had a mileage recorded, which allows a like-for-like comparison.

We only list faults with at least 20 failures and a rate of about 2.0 times that of similar cars, which keeps one-off results out of the list.

Tyre tread depth (rear)

Failed on 34 first tests2.6 times as often as similar carsWear pattern

What it means

Only primary grooves count when tread depth is assessed: those holding the wear indicators, or cut as deep as those when new. Shallower secondary grooves are ignored. Tread depth below the minimum for the vehicle is Dangerous, and so is a pattern not visible over the whole tread, but that second row applies only to vehicles that need the lower minimum.

Data: UK MOT open data, 2025. Compared with cars of the same age and mileage.

Advisories

Other things testers noted as worn or close to failing, more often than on similar cars.

An advisory is a note from the tester about something that has not failed yet. It is an early warning, not a fail.

Coil spring mounting (rear)

Noted on 28 first tests107 times as often as similar carsElevated evidence

Data: UK MOT open data, 2025. Counts cover advisories recorded on failed first tests only, compared with cars of the same age and mileage.

MOT pass rates

How first tests ended, and how the pass rates are counted.

Passed first time: 90in every 100; Passed on the first test.
Fixed at the station: 1in every 100; Failed, then fixed at the test station the same day.
Failed: 9in every 100; Did not pass, and were not fixed at the test station.

First-attempt pass 89.9% of 3,222 first tests (2025): only cars that passed first time count. Official-style pass 91.2%: cars fixed at the test station also count as a pass. The 1 fixed and the 9 not fixed make the 10 in every 100 that did not pass first time.

Petrol and diesel

First testsTypical mileagePassed first time, as testedPassed first time, same mileage

Diesel2,15152,265 miles8889

Petrol79439,940 miles9292

Figures are in every 100 first tests. Cars with more miles usually fail more often, so the same-mileage figure gives every fuel the mileage mix of all the cars in this year.

Same model, other years

Passed first time in every 100, all tested in 2025.

Newer cars are younger, so look for a jump rather than the climb. A year earlier (2024), when these cars were a year younger, 91 in every 100 passed first time.

Year	Passed first time	First tests
2003	63 in every 100	543
2004	62 in every 100	754
2005	63 in every 100	1,307
2006	64 in every 100	2,326
2007	65 in every 100	4,234
2008	65 in every 100	4,491
2009	69 in every 100	3,678
2010	69 in every 100	5,905
2011	73 in every 100	6,249
2012	78 in every 100	7,442
2013	79 in every 100	9,698
2014	79 in every 100	10,009
2015	82 in every 100	10,578
2016	83 in every 100	12,385
2017	85 in every 100	8,782
2018	86 in every 100	7,674
2019	88 in every 100	8,209
2020 This car	90 in every 100	3,222
2021	91 in every 100	4,270
2022	91 in every 100	3,818

If you are buying one

What this year's MOT record means for the decision in front of you.

Mileage makes a modest difference on a 2020 Audi A6.

Of 2020 Audi A6 vehicles with under 35,000 miles, 93 in every 100 passed their 2025 MOT first time. With 68,000 miles or more, 88 in every 100 did.

Under 35,000677 tests

93

35,000–44,000607 tests

90

44,000–54,000 Typical car644 tests

90

54,000–68,000639 tests

90

68,000 and over655 tests

88

Petrol or diesel?

	Typical mileage	Passed first time, as tested	Passed first time, same mileage
Diesel	52,265 miles	88	89
Petrol	39,940 miles	92	92

Figures are in every 100 first tests. Petrol cars look better on the raw figures only because diesel cars have done more miles (typically 52,265 against 39,940). At the same mileage there is no clear difference between the two.

What to check at your mileage

How often each fault turned up on a failed first test, by the car's mileage. Read it as: what is likely to need looking at on a car like the one in front of you.

	Under 35,000	44,000–54,000	68,000 and over
Tyre condition (rear)	1.2	1.6	1.4

Faults per 100 first tests, by the car's mileage at the test.

Every figure here is a first-attempt MOT rate from DVSA open data for this model line, for cars of this model year tested in 2025. Each mileage band holds a fifth of the tests. MOTs do not test engine or gearbox internals, so this is a pre-purchase checklist, not a full reliability score.

FAQs

Short answers about how to read this model-year guide.

Is the 2020 Audi A6 reliable?

The 2020 Audi A6 follows the pattern of the model years either side. Its main cause of failure was Tyre condition (rear), about 16 in every 100 failed tests. In 2025, 89.9% of 3,222 first MOTs on the 2020 Audi A6 passed first time (PRS: items fixed at the station the same day, counted as a fail). The official-style rate including PRS is 91.2%. Among 325 failed first-attempt MOT tests (test year 2025), we highlight MOT failure patterns that show up more often than on cars of a similar age and mileage when the sample is large enough to trust. There is no single reliability score here; this is a pre-purchase checklist built from DVSA open data, not a guarantee for any individual car.

What is most likely to fail on a 2020 Audi A6?

Ranked by how often they were actually recorded, the items that most often failed a 2020 Audi A6 at the first attempt were Tyre condition (rear) (16.3%), each as a share of the year's failed first attempts. That is what goes wrong most often on the car. The common faults table shows a different measure: faults that are unusual compared with similar cars.

How should I read advisories vs fails?

Advisories flag issues noted at the test and are not a fail rate. We show advisory patterns that appear more often than on similar cars among failed first-attempt tests, separate from common failure rows. Use them as early-warning checks, not as a pass/fail score.

What does this Audi A6 2020 MOT report cover?

This page highlights MOT failure patterns for the 2020 Audi A6 (registration year) using UK DVSA open data for the selected test year. Patterns are compared with cars of a similar age and mileage. It is a buyer checklist from MOT defect statistics, not a full service history or manufacturer service-bulletin list.

Does this include engine and gearbox problems?

No. MOT tests do not cover engine internals, gearboxes, or many electronic modules. Patterns here come from MOT defect statistics only and should not be read as engine or gearbox reliability scores.

About this data

How this page is built and what it can (and can't) say.

These figures come from UK MOT open data for this model year. We surface common failure patterns against similar cars, not a full reliability score, and not a pass/fail verdict on any individual vehicle.

2024 2025

What we include

UK Class 4 cars only. Normal MOT tests (not retests); first test per vehicle per calendar year; results pass, PRS, or fail.

Same-day repairs

PRS means the car failed items that were fixed at the test station and then passed the same day. We count PRS as a first-attempt fail in headline rates so same-day repairs do not hide problems.

How we compare

We compare this model year with other Class 4 cars of similar age and mileage in the same test year. This model family is left out of the peer group so the car is not measured against itself.

What this does not cover

MOTs do not cover engine internals, gearboxes, or many electronics; this is not a full reliability score.
Common faults come from MOT defect stats, not manufacturer TSBs or recalls.
Age and mileage matching reduces, but does not remove, differences in how cars were used and maintained.
If the data for a car is too thin to say anything useful, we say so rather than guess.

Contains public sector information licensed under the Open Government Licence v3.0.