Dreams involving spiders can often symbolize feelings of anxiety, fear, or being trapped in a situation. In your dream, the presence of three spiders could suggest that there are multiple sources of stress or concerns in your life. Being stuck in the car with your dad and siblings may represent feelings of being confined or controlled by family dynamics or expectations.

Your anger in the dream towards your dad for placing the spider on your sister's lap indicates a sense of frustration or helplessness in a situation where you feel you have no control. This could reflect real-life feelings about family relationships, where you may feel overwhelmed or unable to express your needs.

To gain insights from this dream, consider reflecting on any current family dynamics or situations in your life where you feel trapped or frustrated. It might be helpful to express your feelings openly with your family to address any underlying tensions.