In Pixar's Cars 3, Smokey was the veteran racer who trained Lightning McQueen's mentor, Doc Hudson.
Lightning learns about Smokey when he travels to Thomasville after seeking a way to regain his competitive edge. Smokey had known Doc Hudson during Doc's racing years and understands the skills and emotional pressures that shaped the older champion.
Smokey helps Lightning connect his own career to Doc's history. He explains that Doc's racing life did not end simply because Doc lacked talent; a crash and the sport's changing culture left him bitter. This history gives Lightning a better understanding of his mentor and of what it means to support another racer.
Smokey is not one of Lightning's original Radiator Springs friends. Louise Nash and River Scott are other retired racers Lightning meets in the film's Thomasville sequence, but Smokey is the character specifically linked to Doc's training.