##You can check the speed of both cars##
During collision, there will be two cases:
- One car is moving, one car is stationary.
- Both cars are moving.
You need to decide which car intentionally hit the other, and obviously, OnTriggerEnter() will not help. To check for speed, use GetComponent<Rigidbody2D>().velocity or GetComponent<Rigidbody>().velocity.
case one - one car is stationary###
In the first case, it's pretty simple. The car that has speed is the car that is hitting the other car.
case two - both cars are moving###
It's tricky for the second case. You can say the car with more speed intentionally hit other car; though it's not always true, it will work most of the time.
