A "celebrity" can be a local, national, or international, but regardless how far the individual's fame went, the vehicle he or she owned is still simply a car or a truck.
Unless the car itself is rare, as was common with film stars in the 1930's with 'one-off' Duesenbergs etc., or a postwar 'special ordered' example as in Post #4, I really don't see how, or why an ordinary off-the-shelf car should be worth more than a similar unit without a history of celebrity ownership.
Craig