I was checking out this video and noticed that Mark Levinson sound systems aren’t in many cars. I’m guessing that it will drive up the cost of the vehicle waaay too much.

And they are all manufactured by a few companies under different brand names. For instance Mark Levinson is owned by Harman International (which is owned by Samsung now) which also owns Harman Kardon, JBL, B&O, Infinity, Bowers & Wilkins, Revel, Lexicon. So, basically all car audio companies are owned by Harman, other than Bose.

He also stated that the car’s design plays a key role in the overall sound quality. I had no idea that the more windows you have and that smaller vehicle’s tend to have lower sound quality. I didn’t hear him touch too much on wattage, but manufacturers are putting in 1000 plus wattage systems in there newer vehicles. I know most people (like myself) like a loud stereo, but most importantly want it to sound amazing.

He's actually incorrect about the size of the vehicle. The larger a vehicle gets generally the harder it is to put a good quality audio system in it.