I'm not going to get in the car with my dad.
Why don't you want to get in the car with your dad?
He's drunk. He will be a danger behind the wheel.
It's okay to refuse an activity that may endanger your life, but its irresponsible to allow him to drive drunk. Otherwise he may end up hurting others or himself.
I'm not helping him break the law and I'm not going to risk getting seriously hurt for his bad choices.
You are right and wise to not get into a car with someone who is drunk. Call them an Uber to get you and them home, or call the police to make sure he doesn't drive home drunk.