The pitch, which is being led by the firm's North American office, is thought to include incumbent Ketchum Pleon, Brands2Life and Edelman.
The chosen agency will promote Hertz's product launches, car-sharing initiatives and special projects, as well as staffing the press office.
Ketchum Pleon has been on board since 2008. Hertz is the world's largest general use car rental firm, operating in more than 8,500 locations in 146 countries.
Hertz was unavailable for comment at the time of going to press.