I did it for a while in the early eighties in California. My biggest problems were 1__Having too many other aggressive sales persons working on my lot and 2__Not so honorable dealership management.
As for experience, there is an old saying that "Green peas sell cars". I suspect it is still...
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A skilled and successful vehicle salesperson friend of mine in the early eighties tried to leave the trade but never could because of a lack of education in the other fields in which he chose to...