Audi A6 2018: reliability & common MOT faults

In 2025, 86 in every 100 first MOTs on a 2018 Audi A6 were passes. Most common reason for a fail: Tyre condition (front).

Summary

The 2018 Audi A6 follows the pattern of the model years either side.

At a glance

How 7,674 first tests went in 2025.

Passed first time
86 in every 100
Did not pass first time
14 in every 1001,109 failed first-attempt tests
The typical car
7 yearsabout 67,353 miles
First tests counted
7,674

What failed most often

  1. Tyre condition (front)16 in every 100 failed tests
  2. Tyre tread depth (front)14 in every 100 failed tests
  3. Diesel engine warning light7 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.

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 21 first tests24 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
86in 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
13in every 100
Did not pass, and were not fixed at the test station.

First-attempt pass 85.5% of 7,674 first tests (2025): only cars that passed first time count. Official-style pass 87.5%: cars fixed at the test station also count as a pass. The 1 fixed and the 13 not fixed make the 14 in every 100 that did not pass first time.

Petrol and diesel

First testsTypical mileagePassed first time, as testedPassed first time, same mileage
Diesel5,65571,496 miles8686
Petrol2,01956,697 miles8584

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.

4060801002005201020152018Older carsNewer cars
40608010020102018Older cars

Newer cars are younger, so look for a jump rather than the climb. A year earlier (2024), when these cars were a year younger, 87 in every 100 passed first time.

YearPassed first timeFirst tests
200363 in every 100543
200462 in every 100754
200563 in every 1001,307
200664 in every 1002,326
200765 in every 1004,234
200865 in every 1004,491
200969 in every 1003,678
201069 in every 1005,905
201173 in every 1006,249
201278 in every 1007,442
201379 in every 1009,698
201479 in every 10010,009
201582 in every 10010,578
201683 in every 10012,385
201785 in every 1008,782
2018 This car86 in every 1007,674
201988 in every 1008,209
202090 in every 1003,222
202191 in every 1004,270
202291 in every 1003,818

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 2018 Audi A6.

Of 2018 Audi A6 vehicles with under 49,000 miles, 89 in every 100 passed their 2025 MOT first time. With 92,000 miles or more, 83 in every 100 did.

Under 49,0001,544 tests
89
49,000–61,0001,492 tests
86
61,000–74,000 Typical car1,611 tests
85
74,000–92,0001,493 tests
84
92,000 and over1,533 tests
83

Petrol or diesel?

Typical mileagePassed first time,
as tested
Passed first time,
same mileage
Diesel71,496 miles8686
Petrol56,697 miles8584

Figures are in every 100 first tests. 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 49,00061,000–74,00092,000 and over
Tyre condition (front)2.12.02.1
Tyre tread depth (front)1.22.12.9
Diesel engine warning light0.61.12.4
Brake pads (rear)0.31.41.6
Coil spring (rear)0.60.70.7

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


When a car fails

58in every 100

of failed cars had one item to fix.

12in every 100

of failed cars had three or more items to fix.

6in every 100

of all first tests had a defect the tester marked dangerous (unsafe to drive away).


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.

The 2018 Audi A6 follows the pattern of the model years either side. Its main cause of failure was Tyre condition (front), about 16 in every 100 failed tests. In 2025, 85.5% of 7,674 first MOTs on the 2018 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 87.5%. Among 1,109 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.
Ranked by how often they were actually recorded, the items that most often failed a 2018 Audi A6 at the first attempt were Tyre condition (front) (16.0%), Tyre tread depth (front) (14.3%) and Diesel engine warning light (7.0%), 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.
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.
This page highlights MOT failure patterns for the 2018 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.
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.

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