Let us consider two vectors A and B.
As per the question, the two vectors are perpendicular to each other.
Hence the angle between them 
We are asked to calculate the resultant of these two vectors.
As per parallelogram law of vector addition, the resultant of two vectors are-

[cos90=0]

This is the way by which we can add two perpendicular vectors.
Answer:
The charges from the thunderstorm flow through the conductive metal
of which the vehicle is made and distribute themselves on the outside surface of the vehicle
Explanation:
It is actually safer to stay inside a car during a thunderstorm rather than standing outside the car. The reason is this, thunder passes electrical charges through a conductor. The body of the vehicle is made of a metal which is a good conductor of electricity. The charges will redistribute themselves on the body of the vehicle (a metallic conductor of electricity) hence the occupants of the car are relatively safe.
The reasons described above makes those inside the vehicle relatively safe compared to a person standing outside.