When Shirley drops Evan home they talk a bit and we can see Evan wearing the safety belt, then we see Shirley, then Evan again but without the safety belt on. At the end of the conversation we see Evan with the safety belt on.
While driving on the freeway with Evan, Charlotte has her hands on the steering wheel which is at a 90 degree turn to the left. She would not be going straight with the wheel like that. You can see that her hands are placed correctly, but with the wheel like that, they would be driving in a circle.