Is it normal for my father to act like this?

One of the most important points we reach as we're growing up is fully comprehending that our parents aren't some sort of gods, but just people who are trying to do their best in a world that basically doesn't give a shit about them or you.

It sounds like your father is having serious problems coping with the pressures on him at work and at home. From what you say, I also suspect that money issues may creating even more tension; nobody works for 18 hours a day unless they need to in order to survive. If your father is a guy who takes his responsibility to provide for his family seriously, money is very tight and he's worrying about how things might get even worse in the future, he could be dealing with feelings that he's a failure as a man, husband and father. If his business isn't thriving, he might be also doubting his abilities and regretting decisions he's made in that part of his life. And he could be feeling that he's trapped in a situation he can't see a way out of. Feeling that you have no agency - that you have no power to control or change the situation you're in - can be soul-destroying.

Your brother's autism might be adding to his stress. Autistic kids can be very challenging to deal with even when parents have no other stresses in their lives. But it's also possible that, at some level, your father blames himself for how his son is, and he could feel a complicated mixture of love, guilt, helplessness and anger at the injustice of it all when dealing with your brother.

I suspect the incident in the car was about him needing a break from all the drama and noise. Most people need at least a little me-time now and then, and if your father is working long hours, forcing himself to make nice with customers who can doubtless sometimes be real dicks, and then comes home to a house that's anything but a calm, peaceful refuge from all that, I can see how he might reach the point where he just has to get away from everything for a few hours in order to restore some sort of equilibrium.

I don't know how old you are, but it's likely that your limited life-experience means there are things going on in your family that you're unable to fully understand at this point. It's also likely that your parents see no reason to try to explain to you and your siblings things like the reality of your family's financial situation. This is a reasonable thing to do, since there's nothing you kids can do to improve that, there's no point in you kids getting stressed-out as well, and most kids have a very tenuous understanding of money and household budgets, never mind the financial aspects of running a small service business.

I can fully understand how you must find this situation very difficult to deal with. You're working with limited information, and it sounds like you don't yet have enough years behind you to have developed a mental model which allows you to understand why people do the things they do. (That's not a criticism and I'm not suggesting you're just a stupid little kid - the part of our brains that allows us to empathise and understand and predict the behaviour of others doesn't finish developing until the mid-twenties.)

The only thing I can suggest is that you look for some moment when you and your father are alone and he's in a relatively positive mood, and you then tell him you know that you don't really understand what's going on, but you can see that he's very unhappy, and that while you also know you probably won't be able to do much, you would like to know if there's anything you can do which would make his life more enjoyable. Of course, before you do this, you should be prepared to walk the walk, rather than just talking the talk. So the question is whether or not you're willing and able to step up and maybe take on some responsibilities around the house and with your siblings which will make life a little easier for both your mum and your father.

He’s just stressed, people do weird things when they’re stressed

Sounds like your dad is super stressed out, and he chose to get out of the car, and walk home instead of losing his temper with your autistic sibling.

You realize that the term "Karen" is a racist term you POS? Do you freely use the N word when referring to blacks? Or fucking dicks when you refer to people from your family?