| Very High: Failure is almost inevitable | 1 in 2 | 10 |
| 1 in 3 | 9 |
|
| High: Repeated failures | 1 in 8 | 8 |
| 1 in 20 | 7 |
|
| Moderate: Occasional failures | 1 in 80 | 6 |
| 1 in 400 | 5 |
|
| 1 in 2000 | 4 |
|
| Low: Relatively few failures | 1 in 15,000 | 3 |
| 1 in 150,000 | 2 |
|
| Remote: Failure is unlikely | 1 in 1,500,000 | 1 |
Source: Automobile Industry Action Group.