Little is known about Harv's personality.
Harv is only seen twice. Lightning McQueen speaks to him through a speakerphone in his trailer.
When McQueen is in his trailer heading to California, Harv gives him a call. Near the end of the film, when Mack arrives in Radiator Springs, Harv asks where McQueen is and tells him to leave right away to get to his race. When McQueen says goodbye to Sally, Harv threatens to fire Mack if he doesn't get Lightning in to the trailer.