Data as of: DVSA MOT results to 2025
Ducati Diavel Carbon vs Harley-Davidson Flstf
The Harley-Davidson Flstf passes its MOT first time more often than the Ducati Diavel Carbon: 89.0% vs 88.7%, a 0.3-point lead.
MOT reliability, side by side
| Metric | Ducati Diavel Carbon | Harley-Davidson Flstf |
|---|---|---|
| First-time pass rate | 88.7% | 89.0% |
| Outright fail rate | 6.0% | 4.9% |
| Vs comparable bikes (age & mileage adjusted) | +1.2 pts | +3.6 pts |
| Engine size | 1,198cc | 1,450cc |
| Rank among all models | #1370 of 5428 | #1269 of 5428 |
| Median miles at test | 8,289 | 12,480 |
| MOT tests analysed | 2,884 | 30,148 |
| Most common failure | brakes | 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 | Ducati Diavel Carbon | Harley-Davidson Flstf |
|---|---|---|
| Lights & signalling | 2.0% | 2.4% |
| Tyres & wheels | 1.5% | 1.0% |
| Brakes | 1.4% | 1.0% |
| Steering & suspension | 1.5% | 0.6% |
| Fuel & exhaust | 0.2% | 0.6% |
| Structure & body | 0.4% | 0.3% |
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 | Ducati Diavel Carbon | Harley-Davidson Flstf |
|---|---|---|
| 2018 | 85.1% | 89.6% |
| 2019 | 88.8% | 88.6% |
| 2020 | 90.1% | 91.2% |
| 2021 | 89.2% | 90.4% |
| 2022 | 85.7% | 90.3% |
| 2023 | 91.2% | 89.7% |
| 2024 | 92.9% | 90.4% |
| 2025 | 89.0% | 91.8% |
Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.
Pass rate by mileage
| Mileage | Ducati Diavel Carbon | Harley-Davidson Flstf |
|---|---|---|
| 0k-10k miles | 89.9% | 90.1% |
| 10k-20k miles | 87.0% | 88.7% |
| 20k-30k miles | 84.7% | 87.8% |
| 30k-40k miles | 91.8% | 87.5% |
Bands with fewer than 30 tests for either bike are left out.
Ducati Diavel Carbon vs Harley-Davidson Flstf FAQ
Which is more reliable, the Ducati Diavel Carbon or the Harley-Davidson Flstf?
The Harley-Davidson Flstf passes its MOT first time more often than the Ducati Diavel Carbon: 89.0% vs 88.7%, a 0.3-point lead. Adjusted for age, mileage and test class, the Harley-Davidson Flstf still comes out ahead: +1.2 points vs comparable bikes for the Ducati Diavel Carbon, +3.6 for the Harley-Davidson Flstf. An MOT checks roadworthiness items, not engine or gearbox internals.
What does the Ducati Diavel Carbon fail its MOT on most?
Lights & signalling: 2.0% of Ducati Diavel Carbon MOT tests failed on it, then tyres & wheels (1.5%).
What does the Harley-Davidson Flstf fail its MOT on most?
Lights & signalling: 2.4% of Harley-Davidson Flstf MOT tests failed on it, then tyres & wheels (1.0%).
Which holds up better at high mileage, the Ducati Diavel Carbon or the Harley-Davidson Flstf?
At 30k-40k miles the Ducati Diavel Carbon passes first time more often: 91.8% for the Ducati Diavel Carbon vs 87.5% for the Harley-Davidson Flstf.
See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.