As drivers we have a legal responsibility to drive our cars in a safe and careful manner. And this responsibility extends to people driving in other cars, pedestrians, cyclists, and it also extends to the passengers in our cars.
When the driver of a car does something that they shouldn't do like drinking, speeding, running a red light, texting or talking on their cellphone, and that driver gets in a single vehicle accident and the passenger is injured, then they may have a claim against the driver. Even if there are no other cars involved.
If you are involved in a one car accident as a passenger, talk to a lawyer to see if you have a right to make a claim against the driver.