Premise: Cars Toons is a series of American computer-animated short films by Pixar. It features Lightning McQueen and Mater from "Cars". Larry the Cable Guy reprises his role as Mater while Keith Ferguson replaces Owen Wilson as Lightning McQueen (until "The Radiator Springs 500 ½" when Wilson reprises his role).
Hypothesis: Owen Wilson has been the sole voice of Lightning McQueen in the "Cars" series.