Their skulls make good fertilizer.
Just kidding, I sold cars for a while myself many years ago. Thought I'd love being around cars all day. What a mistake. Hated the scurvy GM and ended up in a yelling match with him on the salesfloor on a crowded Saturday. The whole thing ended with me telling him to give his trophy wife back to the teenage kid he bought her from and to lie to customers his own damn self. Later that day one of the other salesmen told me that he told the customers who overheard the exchange that he found out I was a felon and released me and apologized to them because I "didn't leave quietly." I have to admit, it was a quick thinking save on his part.
Hope you have a better GM and a better career at it.
And for the record, for every bad salesman there's a jerk customer that deserves him