Data as of: DVSA MOT results to 2025
Ajs Firefox vs Piaggio Zip
The Piaggio Zip passes its MOT first time more often than the Ajs Firefox: 71.3% vs 69.4%, a 1.9-point lead.
MOT reliability, side by side
| Metric | Ajs Firefox | Piaggio Zip |
|---|---|---|
| First-time pass rate | 69.4% | 71.3% |
| Outright fail rate | 21.9% | 20.4% |
| Vs comparable bikes (age & mileage adjusted) | -5.2 pts | -1.0 pts |
| Engine size | 49cc | 49cc |
| Rank among all models | #4778 of 5428 | #4631 of 5428 |
| Median miles at test | 6,168 | 8,882 |
| MOT tests analysed | 1,537 | 78,993 |
| Most common failure | lamps and reflectors | lighting and signalling |
First-time outcomes on normal tests, 2005–2025. "Most common failure" is the component group with the most recorded defects on failed tests. Read pass rates against test counts: a smaller sample is noisier. Source: DVSA anonymised MOT results.
"Vs comparable bikes" is the first-time pass rate minus the rate expected for each bike's own mix of age, mileage and test class, in percentage points: positive means better than comparable bikes. How this works.
What fails, side by side
| Component | Ajs Firefox | Piaggio Zip |
|---|---|---|
| Lights & signalling | 13.4% | 11.9% |
| Steering & suspension | 9.8% | 9.2% |
| Brakes | 7.3% | 6.5% |
| Tyres & wheels | 2.9% | 4.0% |
| Structure & body | 4.0% | 1.6% |
| Fuel & exhaust | 0.1% | 2.5% |
A test that fails on two components counts once in each. Component links go to the bikes most likely to fail on it.
Pass rate by test year
| Test year | Ajs Firefox | Piaggio Zip |
|---|---|---|
| 2018 | 61.8% | 72.9% |
| 2019 | 70.1% | 73.0% |
| 2020 | 77.0% | 73.1% |
| 2021 | 64.4% | 73.3% |
| 2022 | 69.2% | 74.5% |
| 2023 | 67.9% | 74.1% |
| 2024 | 67.0% | 73.4% |
| 2025 | 73.3% | 76.2% |
Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.
Pass rate by mileage
| Mileage | Ajs Firefox | Piaggio Zip |
|---|---|---|
| 0k-10k miles | 71.1% | 75.2% |
| 10k-20k miles | 62.5% | 66.7% |
| 20k-30k miles | 50.0% | 64.4% |
Bands with fewer than 30 tests for either bike are left out.
Ajs Firefox vs Piaggio Zip FAQ
Which is more reliable, the Ajs Firefox or the Piaggio Zip?
The Piaggio Zip passes its MOT first time more often than the Ajs Firefox: 71.3% vs 69.4%, a 1.9-point lead. Adjusted for age, mileage and test class, the Piaggio Zip still comes out ahead: -5.2 points vs comparable bikes for the Ajs Firefox, -1.0 for the Piaggio Zip. An MOT checks roadworthiness items, not engine or gearbox internals.
What does the Ajs Firefox fail its MOT on most?
Lights & signalling: 13.4% of Ajs Firefox MOT tests failed on it, then steering & suspension (9.8%).
What does the Piaggio Zip fail its MOT on most?
Lights & signalling: 11.9% of Piaggio Zip MOT tests failed on it, then steering & suspension (9.2%).
Which holds up better at high mileage, the Ajs Firefox or the Piaggio Zip?
At 20k-30k miles the Piaggio Zip passes first time more often: 50.0% for the Ajs Firefox vs 64.4% for the Piaggio Zip.
See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.