Always grab the dashboard or doorhandle and yell "Whoa!"
Always tell the driver to slow down or speed up.
Constantly remind the driver of road conditions.
Whenever possible, adjust all the dashboard controls, including the radio, heat, and fan.
Remember: If there is a mirror on the passenger side door, it's there for the passenger. Feel free to adjust it at will.
When at a traffic light, inform the driver the millisecond the light turns green.