My cousin had a 45 record deck under his dash. I believe it was a Sparkomatic, but I could be wrong on that. You put in one record at a time and it had some sort of pressure device that pressed on the needle to keep it from skipping when the car went over bumps. It didn’t work very well, and sounded like s#it but I have never seen another one.
I’ve heard of such devices but never have seen one. Sounds like it would be more trouble than it was worth.