I don't love my father.
That's unfortunate. Why do you not love him?
He was never there when I needed him most.
It is hard not to be resentful if a parent is not around, but you should try to love your parents. Try to have a relationship with your family, even when you are an adult.
I wanted to be helpful and fix his car, which I did. And even after that he treats me like shit.
I commend you for trying to help fix his car despite having resentment issues, as it's good to love your family members and put forth effort in having a good relationship. Have you spoke to him about your feelings about him not being there for you? Perhaps he is unaware of his actions.