The probability of a traffic accident being fatal is much higher in a **two-wheeled vehicle** than in a car. This is due to several factors:

- **Physical protection**: Two-wheeled vehicles, such as motorcycles, offer less physical protection to the driver compared to cars. In the event of an accident, the driver of a two-wheeled vehicle is more exposed to suffering serious or fatal injuries.

- **Helmet use**: Although it is mandatory, some drivers of two-wheeled vehicles do not use a helmet, which increases the risk of fatal injuries in the event of an accident. The lack of a helmet is a factor that contributes to the severity of accidents in these vehicles.

- **Stability and control**: Two-wheeled vehicles are less stable than four-wheeled ones, which can make them more prone to losing control, especially in adverse conditions or when taking curves at high speed.

- **Visibility and size**: Two-wheeled vehicles are smaller and less visible to other drivers, which can increase the risk of collisions.

These combined factors make accidents in two-wheeled vehicles more likely to result in fatalities compared to cars.