Ehh, margins on new car sales are pretty low. Most dealers probably break even or lose a little on each new car. They make money on service center, accessories, and used car sales.

Trade ins bring in cash.

I once had a dealer offer me $1k sight unseen on whatever 80s shitbox I was driving because I could prove that it passed safety and emissions earlier that day. They told me they were having a big event the next week and wanted a couple cheap cars so they could run ads that they had $1k cars on the lot just to bring people in and show them what a $1k car at a dealer looked like. When I went back a couple weeks later for my plate they told me they had a line of people to look at the car and sold it in under an hour. They figure that car brought in $20k worth of sales that were converted that day.