Im pretty sure car companies and dealers aren't in the car business, but rather the finance business. Unlike a personal loan for home improvement or a trip, it's for a tangible good with an easy to repossess product that can sell multiple times. They may not make much money on the sale (sometimes only $1000 over cost on a new car) but then it's 5% on that loan. Then its 8% again when they sell that same car a second time. They make money as the car depreciates, since they sell the car for 50k once, then maybe 30k the second time, and 15k each time after that.
we had a super d-bag finance guy when we last bought a car. my wife's was totaled and we needed a new one before getting the pay out on the last, so went through a credit union for 1%. why not? anyway, he kept telling me it was illegal to secure my own money, I had to go through them, and my credit union rates were 3%. He would have gotten that additional 2. I may have reminded him that I was smarter than him, knew my shit, and if he didn't shut his mouth my pregnant and injured wife was going to unleash hell on his supervisor.
Cleared those issues right up.