I'm thinking of crashing the car because it's not mine.
Why are you driving someone else's car?
I asked my friend if I could borrow his car.
Crashing another person's car is wrong. You would not want someone to crash your car, so you should extend the same courtesy to others.
I'm not going to crash it.
Well I'm glad you reconsidered, your friend would be awfully upset if he found out you crashed his car.