Model Reports 8 min read Updated 11 Sep 2026 DVSA open data · 3,007 tests analysed

Ford Mustang 2021: reliability & common MOT faults

299 first-attempt MOT failures were recorded on the 2021 Ford Mustang in 2025. The items recorded most often on them were Tyres — Condition (front) and Tread depth (rear). Figures are among first-attempt failed MOT tests, not among all tests.

2021 Mustangs break the Mustang's own run — at 90.1% they land 2.0 pp above the midpoint of the 2020 and 2022 cars either side.

First-attempt pass

90.1%

of 3,007 first tests (2025)

First tests

3,007

test year 2025

Failed first attempts

299

failed first-attempt tests

Most common fail

29.1%

Tyres — Condition (front)

MOT pass rates

First-attempt and official-style rates among class 4 first tests of the year.

First-attempt pass

90.1%

of 3,007 first tests (2025)

Official-style pass

91.7%

incl. same-day PRS fixes

First tests

3,007

class 4 · first MOT of the year

Typical age 4.0 yrs · median mileage 33,675 mi

vs 2024: +0.3 pp first-attempt

Note:

  • Class 4 cars · first MOT of the year per vehicle · P/PRS/F outcomes (2025 data).
  • PRS (fixed at the station the same day) counts as a fail in the first-attempt rate.
  • Raw outcomes for this cohort — not adjusted for age, mileage, or peer mix.
  • MOT doesn't test engine or gearbox internals.

Wear patterns

Usage and mileage effects that often track road use rather than model design.

These patterns look like wear or usage effects rather than model-specific design faults. Tyres, brake friction material, and alignment-related defects often track mileage and road use.

Pattern Location Failures vs similar cars Share of fails Confidence
Tread depth (rear)
Tyres > Tread depth
 Rear 61 ×6.4 20.4% Wear
Note: These patterns are not treated as a model design fault in our common-faults ranking.

If you are buying one

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

This year outperforms the Mustang's own age curve — it holds up better than its place in the model's run would predict.

What to check on a 2021 Mustang

The items that failed 2021 Mustangs most often, as a share of the year's failed first attempts. This is what goes wrong, not what is unusual — the table further up the page covers that.

  • Tyres — Condition (front) — recorded on 29.1% of failed first attempts
  • Tread depth (rear) — recorded on 20.4% of failed first attempts

Every figure here is a first-attempt MOT rate from DVSA open data for this model line. 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.

2021 Mustangs break the Mustang's own run — at 90.1% they land 2.0 pp above the midpoint of the 2020 and 2022 cars either side. In 2025, 90.1% of 3,007 first MOTs on the 2021 Ford Mustang passed first time (PRS — items fixed at the station the same day — counted as a fail). The official-style rate including PRS is 91.7%. Among 299 failed first-attempt MOT tests (test year 2025), we highlight MOT failure patterns tha…
Ranked by how often they were actually recorded, the items that failed 2021 Ford Mustangs most often at the first attempt were Tyres — Condition (front) (29.1%) and Tread depth (rear) (20.4%) — each as a share of the year's failed first attempts. That is what goes wrong on the car. It is a different question from which patterns are unusual for the class, which the common-faults table answers.
This page highlights MOT failure patterns for the 2021 Ford Mustang (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.
  • We never invent pass rates, star scores, or ranks when those data marts are missing.

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

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