Data as of: DVSA MOT results to 2025
Ducati Diavel vs Harley-Davidson Flstf
The Ducati Diavel passes its MOT first time more often than the Harley-Davidson Flstf: 90.3% vs 89.0%, a 1.3-point lead.
MOT reliability, side by side
| Metric | Ducati Diavel | Harley-Davidson Flstf |
|---|---|---|
| First-time pass rate | 90.3% | 89.0% |
| Outright fail rate | 5.4% | 4.9% |
| Vs comparable bikes (age & mileage adjusted) | +2.8 pts | +3.6 pts |
| Engine size | 1,198cc | 1,450cc |
| Rank among all models | #854 of 5428 | #1269 of 5428 |
| Median miles at test | 8,340 | 12,480 |
| MOT tests analysed | 8,740 | 30,148 |
| 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 | Ducati Diavel | Harley-Davidson Flstf |
|---|---|---|
| Lights & signalling | 1.8% | 2.4% |
| Brakes | 1.4% | 1.0% |
| Steering & suspension | 1.4% | 0.6% |
| Tyres & wheels | 1.0% | 1.0% |
| Fuel & exhaust | 0.1% | 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 | Harley-Davidson Flstf |
|---|---|---|
| 2018 | 89.7% | 89.6% |
| 2019 | 89.3% | 88.6% |
| 2020 | 92.0% | 91.2% |
| 2021 | 91.8% | 90.4% |
| 2022 | 91.7% | 90.3% |
| 2023 | 90.2% | 89.7% |
| 2024 | 90.7% | 90.4% |
| 2025 | 92.6% | 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 | Harley-Davidson Flstf |
|---|---|---|
| 0k-10k miles | 91.7% | 90.1% |
| 10k-20k miles | 88.8% | 88.7% |
| 20k-30k miles | 85.9% | 87.8% |
| 30k-40k miles | 87.8% | 87.5% |
Bands with fewer than 30 tests for either bike are left out.
Ducati Diavel vs Harley-Davidson Flstf FAQ
Which is more reliable, the Ducati Diavel or the Harley-Davidson Flstf?
The Ducati Diavel passes its MOT first time more often than the Harley-Davidson Flstf: 90.3% vs 89.0%, a 1.3-point lead. Adjusted for age, mileage and test class the two are level (+2.8 vs +3.6 points against comparable bikes), so the raw gap is mostly down to how old and how used each fleet is. An MOT checks roadworthiness items, not engine or gearbox internals.
What does the Ducati Diavel fail its MOT on most?
Lights & signalling: 1.8% of Ducati Diavel MOT tests failed on it, then brakes (1.4%).
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 brakes (1.0%).
Which holds up better at high mileage, the Ducati Diavel or the Harley-Davidson Flstf?
They are level: at 30k-40k miles the Ducati Diavel passes 87.8% first time and the Harley-Davidson Flstf 87.5%.
See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.