Dan Blocker, who played Hoss on Bonanza, was the 1st tv star to be hired by a car dealership, to help sell cars. Nickey

 The source for this bit of trivia, is the MCACN magazine, and I guess they meant that it wasn't a celeb hired by the manufacturer, as so many radio and early tv stars were part of the advertising of cars in magazines, newspapers, and commercials.

Maybe he was the 1st tv star that was hired by a dealership, and not the manufacturer. 

But what's the real interesting point, is that he was hired by Nickey