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Ford Mustang S550 (6th gen) (2015-2023) reliability

At a glance

Ford Mustang S550 (6th gen) built around 2018: more fails still not passed 3 days later

Ford Mustang S550 (6th gen) models built around 2018 fail an MOT and still haven’t passed 3 days later more often than similar cars the same age. Look closely at the tyres on any car you view.

Looking at a Ford Mustang S550 (6th gen) right now?

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Key figure

4.9% of MOT tests on Ford Mustang S550 (6th gen) models built around 2018 failed and still hadn’t passed 3 days later. For similar cars the same age, it was 2.9%.

Most common issue

The most common MOT issue on Ford Mustang S550 (6th gen) models built around 2018 involves the tyres.

Ford Mustang S550 (6th gen)
No reliability rating: too close to call between ratings2015-2023CoupePETROL

Based on 11,566 tests of Mustang models registered 2015-2023.

About 1 in 12 petrol Mustang cars registered in 2022 (7.7%) failed their first MOT.

Based on 595 first MOTs (DVSA MOT results, 2025).

About 1 in 20 Mustang S550 (6th gen) MOTs (4.9%) failed and still hadn't passed 3 days later. That's for cars built around 2018 (7 years old), all fuels combined.

Based on 2,337 tests (DVSA MOT results, 2025). A fail that passed a retest within 3 days, even the same day, isn't counted. Nor is a fail with no later MOT on record.

About 1 in 20 Mustang S550 (6th gen) MOTs (5.3%) found at least one dangerous defect. These are cars built around 2018 (7 years old).

Based on 2,337 tests (DVSA MOT results, 2025). Dangerous is the most serious grade an MOT gives: a direct risk to road safety.

S550 (6th gen) fail rate by age

Below typicalAbove typicalHigh (28% or more)Highest fail rateUK average for cars this age
Age / builtFail rateMOT tests
3 yearsbuilt around 2022
7239.3%
4 yearsbuilt around 2021
76910.8%
5 yearsbuilt around 2020
1,33212.3%
6 yearsbuilt around 2019
1,67015.1%
7 yearsbuilt around 2018
2,33714.8%
8 yearsbuilt around 2017
2,59415.4%
9 yearsbuilt around 2016
2,05215.8%
10 yearsbuilt around 2015
8910.1%

Fail rate is the share of MOT tests that ended in a fail. Retests count as tests. How we count fail rates Build years are worked out from age, so they are approximate. Tests counted are 2025 MOTs. Highest fail rate at 9 years old.

How the Mustang S550 (6th gen) compares

At each age below, see how the Mustang S550 (6th gen) holds up against other cars the same age. The averages combine all fuel types.

Based on 306,729 tests across 17 Ford models, built around 2018 (7 years old).

Below typicalAbove typicalHigh (28% or more)Highest fail rateFord average
Age / builtFail rateMOT tests
3 yearsbuilt around 2022
7239.3%
4 yearsbuilt around 2021
76910.8%
5 yearsbuilt around 2020
1,33212.3%
6 yearsbuilt around 2019
1,67015.1%
7 yearsbuilt around 2018
2,33714.8%
8 yearsbuilt around 2017
2,59415.4%
9 yearsbuilt around 2016
2,05215.8%
10 yearsbuilt around 2015
8910.1%

Fail rate is the share of MOT tests that ended in a fail. Retests count as tests. How we count fail rates Build years are worked out from age, so they are approximate. Tests counted are 2025 MOTs.

What to check before viewing

The model's most common MOT issues, turned into things you can ask about or look for.

Brake discs

High priority

Ask for the date and mileage of the last disc replacement; visually check for a deep wear lip and rust pitting on each disc.

Brake pads

High priority

Ask when the pads were last replaced and check the warning-light history.

Tyres

Worth checking

Check tread depth across the full width on all four; uneven wear suggests alignment or suspension issues.

Handbrake / parking brake

Worth checking

Test the handbrake on a slope and confirm it holds without ratcheting through to the end.

Vehicle-specific check

Worth checking

Check the car’s number plate on MOT Wise to see its own MOT history and any recalls for its build years.

Other coupes to compare

Other coupes, with each one's figures taken at the same age as the Mustang S550 (6th gen).

  1. 1

    Porsche 911

    Same body type, tested at the same age

    Fail rate
    5.3%
    Fail, no pass in 3 days
    1.4%
    Dangerous
    1.6%
    Still registered at 10 years
    94%

    Lower fail rate: 5.3%, against 14.8% for the Ford Mustang S550 (6th gen), both built around 2018.

    2,547 MOT tests on cars built around 2018

  2. 2

    Porsche Cayman

    Same body type, tested at the same age

    Fail rate
    5.5%
    Fail, no pass in 3 days
    1.3%
    Dangerous
    2.4%
    Still registered at 10 years
    93%

    Lower fail rate: 5.5%, against 14.8% for the Ford Mustang S550 (6th gen), both built around 2018.

    1,235 MOT tests on cars built around 2018

  3. 3

    Jaguar F-Type

    Same body type, tested at the same age

    Fail rate
    8.6%
    Fail, no pass in 3 days
    1.9%
    Dangerous
    2.4%
    Still registered at 10 years
    95.3%

    Lower fail rate: 8.6%, against 14.8% for the Ford Mustang S550 (6th gen), both built around 2018.

    3 critical recall campaigns matching this model/build period.

    2,085 MOT tests on cars built around 2018

  4. 4

    Audi TT

    Same body type, tested at the same age

    Fail rate
    10.4%
    Fail, no pass in 3 days
    1.8%
    Dangerous
    4.9%
    Still registered at 10 years
    95.5%

    Lower fail rate: 10.4%, against 14.8% for the Ford Mustang S550 (6th gen), both built around 2018.

    6,783 MOT tests on cars built around 2018

Fail rate
= the share of MOT tests that ended in a fail. Retests count as tests.
Fail, no pass in 3 days
= the share of MOT tests that failed and still hadn't passed 3 days later. A fail that passed a retest within 3 days, even the same day, isn't counted.
Dangerous
= the share of MOT tests where the tester marked a fault as dangerous. It is against the law to drive the car until it is fixed.
Still registered at 10 years
= the share of cars still registered (taxed or declared off the road) 10 years after they were first registered.

How many are still registered

Not enough registration data to show this for the Ford Mustang.

The share still registered can reflect demand, the cost of repairs, exports, write-offs and how owners use the car. It isn't proof of how long the car lasts mechanically.

Recall context

49 recalls in all

14 of the 49 Mustang S550 (6th gen) recalls cover cars built in these years.

  • 1 Critical
  • 13 more

Top concerns

  • Fire may occur
  • 25S75 cross carline - low pressure fuel pump potential failure
  • 26C16 Mustang - lane keeping system software update

For the exact car, check GOV.UK's recall checker with the number plate.

What has gone wrong on Mustang S550 (6th gen) cars built around 2018

The share of petrol cars that have ever failed an MOT on each part of the car. Based on 191 cars.

Structural systems

Emissions
5%
Suspension
4%
Steering
1%
Bodywork
1%

Wear items

Tyres
20%
Brakes
16%
Lighting
5%

Fail rate by engine size, built around 2018 (7 years old)

Engine sizes across all petrol Mustang tests (not specific to S550 (6th gen)).

2.0 to 3.0 litres17.1%569 tests3.0 litres or more14.1%1,768 tests
How Mustang S550 (6th gen) cars have aged

How Mustang S550 (6th gen) cars have aged

How fail rates have changed as these cars got older. Each line follows cars first registered in about the same year across several years of MOT data. Not a prediction for any one car.

Some lines cover only a year or two, so read this as a rough guide.

0%10%345678910Age at MOTBuilt around 2021, 3 years old at the time of MOT: 12.3% (424 tests, 2024 data)Built around 2021, 4 years old at the time of MOT: 8.7% (358 tests, 2025 data)2021Built around 2020, 3 years old at the time of MOT: 11.4% (848 tests, 2023 data)Built around 2020, 4 years old at the time of MOT: 11.8% (811 tests, 2024 data)Built around 2020, 5 years old at the time of MOT: 11.5% (749 tests, 2025 data)2020Built around 2019, 3 years old at the time of MOT: 13.5% (980 tests, 2022 data)Built around 2019, 4 years old at the time of MOT: 12.8% (904 tests, 2023 data)Built around 2019, 5 years old at the time of MOT: 15.1% (861 tests, 2024 data)Built around 2019, 6 years old at the time of MOT: 14.2% (809 tests, 2025 data)2019Built around 2018, 3 years old at the time of MOT: 9.8% (1,947 tests, 2021 data)Built around 2018, 4 years old at the time of MOT: 12.0% (1,731 tests, 2022 data)Built around 2018, 5 years old at the time of MOT: 14.7% (1,679 tests, 2023 data)Built around 2018, 6 years old at the time of MOT: 16.1% (1,635 tests, 2024 data)Built around 2018, 7 years old at the time of MOT: 13.7% (1,565 tests, 2025 data)2018Built around 2017, 4 years old at the time of MOT: 11.8% (1,601 tests, 2021 data)Built around 2017, 5 years old at the time of MOT: 11.8% (1,563 tests, 2022 data)Built around 2017, 6 years old at the time of MOT: 14.7% (1,485 tests, 2023 data)Built around 2017, 7 years old at the time of MOT: 14.2% (1,462 tests, 2024 data)Built around 2017, 8 years old at the time of MOT: 14.6% (1,415 tests, 2025 data)2017Built around 2016, 5 years old at the time of MOT: 13.0% (2,039 tests, 2021 data)Built around 2016, 6 years old at the time of MOT: 15.2% (2,028 tests, 2022 data)Built around 2016, 7 years old at the time of MOT: 15.9% (1,912 tests, 2023 data)Built around 2016, 8 years old at the time of MOT: 16.0% (1,874 tests, 2024 data)Built around 2016, 9 years old at the time of MOT: 16.0% (1,767 tests, 2025 data)2016Built around 2015, 6 years old at the time of MOT: 10.2% (137 tests, 2021 data)Built around 2015, 7 years old at the time of MOT: 12.9% (132 tests, 2022 data)Built around 2015, 8 years old at the time of MOT: 13.0% (115 tests, 2023 data)Built around 2015, 9 years old at the time of MOT: 12.6% (111 tests, 2024 data)Built around 2015, 10 years old at the time of MOT: 10.1% (89 tests, 2025 data)2015
First registered around 2021First registered around 2020First registered around 2019First registered around 2018
How each part holds up as S550 (6th gen) cars age

How each part holds up as S550 (6th gen) cars age

The share of petrol cars built 2017-2020 that have ever failed an MOT on each part of the car. Rates usually rise with age, but can dip slightly as cars leave the road.

Part of the car5 years6 years7 years8 years
Suspension2%2%4%5%
Brakes7%16%16%23%
Emissions3%1%5%7%
Tyres22%22%20%23%
Lighting3%3%5%9%
Bodywork2%No figure1%No figure
SteeringNo figureNo figure1%2%
Corrosion2%0%0%0%

Based on petrol cars in the 2017-2020 build-year band, from 59 to 191 cars at each age.

S550 (6th gen) variants compared
All generations of this modelEnough data

Most common issues on Ford Mustangs of this age

This list covers every Ford Mustang built around 2018, whichever generation it is. We don't have a defect list for the S550 (6th gen) on its own.

Most common advisories and fails

In order of the share of MOT tests that recorded each one

  1. 1
    Advisory

    Tyre worn close to the legal limit or worn on the edge

    15.8%
    Advisory: 590Fail: 52 (8% of the times it was found)
  2. 2
    Advisory

    Tyre slightly damaged, cracking or perishing

    7.5%
    Advisory: 230Fail: 68 (23% of the times it was found)
  3. 3
    Advisory

    Brake disc worn, pitted or scored, but not seriously weakened

    5.7%
    Advisory: 213Fail: 0 (0% of the times it was found)
  4. 4
    Advisory

    Brake pads wearing thin

    5.4%
    Advisory: 151Fail: 13 (8% of the times it was found)
  5. 5
    Major

    Handbrake weaker than required

    4.0%
    Advisory: 7Fail: 87 (93% of the times it was found)

Based on 2,337 tests

Looking at a Ford Mustang S550 (6th gen) right now?

Enter its number plate to see its full MOT history, risk rating and running costs.

Frequently asked questions

Built around 2018 (7 years old), the Ford Mustang S550 (6th gen) (2015-2023) fails MOTs at about the rate typical for this age. This is based on 2,337 7-year-old MOT tests from DVSA data. Each retest counts as a test.

*The build year is worked out from the date a car was first used on UK roads. For most cars this matches when it was registered, but imports may differ by a few months.

Data sourced from DVSA MOT History API. From 11,566 MOT tests on Ford Mustangs first registered between 2015-2023. These figures are a guide, not a guarantee.