1981 MG B/Gt — MOT failures & pass rate
633 MOT tests on the 1981 MG B/Gt are in this dataset, and 79.8% of them passed. That is 3.0 percentage points worse than all cars of a similar age, which fail at 17.2%. Failures cluster in emissions & environmental, lighting & signalling and brakes.
What the MOT record shows
No single area dominates — emissions & environmental (10.3%) and lighting & signalling (10.1%) are close, so failures are spread across several systems rather than one weak point.
At component level the recurring items are non catalyst emissions, washers and headlamp aim — non catalyst emissions alone was recorded 70 times.
Mileage matters less than usual here: the 1981 B/Gt fails 19.4% of the time in the 0-30k band and 21.1% at 90-120k, a spread of only 1.8 points.
Advisories point at the next bill rather than this one: suspension was flagged on 19.3% of tests without failing them.
The trend is improving — the fail rate fell from 23.0% in 2021 to 17.3% in 2025, as the worst-kept examples leave the fleet.
How it compares
Top failure categories
| # | Category | % of tests affected | Tests |
|---|---|---|---|
| 1 | Emissions & environmental | 10.3% | 65 |
| 2 | Lighting & signalling | 10.1% | 64 |
| 3 | Brakes | 6.2% | 39 |
| 4 | Visibility | 6.2% | 39 |
| 5 | Suspension | 4.7% | 30 |
| 6 | Body, structure & corrosion | 2.8% | 18 |
Most common specific failures
The exact components most often recorded as failures — more specific than the categories above.
| # | Failure item | Times recorded |
|---|---|---|
| 1 | Non catalyst emissions | 70 |
| 2 | Washers | 33 |
| 3 | Headlamp aim | 23 |
| 4 | Rear fog lamp | 21 |
| 5 | Position lamp | 20 |
| 6 | Service brake imbalance | 19 |
Top advisory categories
Advisories aren't failures, but they flag work likely needed soon — useful when budgeting.
| # | Category | % of tests with advisory | Tests |
|---|---|---|---|
| 1 | Suspension | 19.3% | 122 |
| 2 | Emissions & environmental | 17.1% | 108 |
| 3 | Brakes | 10.0% | 63 |
| 4 | Other defects | 6.8% | 43 |
| 5 | Tyres | 6.8% | 43 |
| 6 | Body, structure & corrosion | 4.9% | 31 |
Failure rate by mileage
Higher-mileage cars tend to fail more — often the most useful guide to real condition.
| Mileage band | Tests | Fail rate |
|---|---|---|
| 0-30k | 160 | 19.4% |
| 30-60k | 181 | 18.2% |
| 60-90k | 239 | 22.2% |
| 90-120k | 52 | 21.1% |
Trend over time
| Dataset year | Tests | Fail rate |
|---|---|---|
| 2021 | 217 | 23.0% |
| 2022 | 113 | 17.7% |
| 2023 | 113 | 20.3% |
| 2024 | 92 | 19.6% |
| 2025 | 98 | 17.3% |
What to check before buying a 1981 B/Gt
On a 1981 B/Gt, emissions & environmental is what the MOT record says goes wrong most — it appeared in 10.3% of tests. Check these areas before you commit.
- Emissions & environmental (10.3% of tests): More common on older diesels (DPF/EGR) — can be expensive; check for warning lights and smoke. Typical repair: £100–£600.
- Lighting & signalling (10.1% of tests): Often a cheap bulb, but persistent issues can mean wiring or corrosion in the units. Typical repair: £10–£150.
- Brakes (6.2% of tests): Pads/discs are routine wear; binding, imbalance or corroded pipes are more serious — test for pulling under braking. Typical repair: £100–£350 per axle.
Repair costs are rough UK ballpark ranges to set expectations, not quotes — actual prices vary widely by car, parts and garage.
Frequently asked questions
How many 1981 MG B/Gts pass their MOT?
79.8% of the 633 1981 MG B/Gt MOT tests in this dataset passed — a 20.2% fail rate.
What is the most common MOT failure on a 1981 MG B/Gt?
Emissions & environmental, recorded in 10.3% of tests, followed by lighting & signalling (10.1%).
Does the 1981 B/Gt get worse with mileage?
Its MOT fail rate rises from 19.4% in the 0-30k band to 21.1% in the 90-120k band.
Methodology & source. Based on 633 MOT tests. Dataset: DVSA MOT testing data (2021,2022,2023,2024,2025). Data last updated 2026-07-27. Figures reflect MOT-testable defects only — read the methodology for how these are calculated and what they don't measure.