One simple tip to help prevent serious injury or even death is the following; no matter how much of a rush you’re in, do NOT put anything hard that weighs more than a pound or two (e.g., a laptop, full water bottle, groceries, etc.) on the car seat next to you.
In a car accident these objects can essentially become a ballistic missile if it is propelled through the air. If it strikes you or another passenger, serious injury is extremely likely. Use the vehicle’s trunk for storing things in transport – that’s what it’s there for!