Is it possible to install a PC inside your car?

I was thinking about my car a few days ago and I’m in need of putting in a better stereo system. The more I thought of it, I thought how nice it would be to have my PC inside my car. Of course not my desktop, for it would have to be alot smaller. Maybe even a notebook. Has anyone ever seen this done or know how you’d hook up a pc to the car speakers? Would it be possible to buy one of those mini pc notebooks and dissassemble it to fit inside a dash board? How could you connect it to the speakers? I’d assume youd have to use a power converter to run the pc