Thanks. You're wrong for some of this, or mostly repeat informations found by Joao, but you make one big step by giving us the correct year for the Plymouth. Wrong model though. The Triumph Mayflower doesn't belong to this puzzle.
Now we have:
Character A (or C, it doesn't matter):
Christopher Jones (Joao), Captain of the Mayflower, played by
Spencer Tracy (Otto Puzzell)
Link 1 (vehicle):
The Mayflower (Joao)
Link 2:
Plymouth "Mayflower" hood ornament (Joao)
Link 3 (car):
1937 Plymouth DeLuxe Coupe (streamliner)
Link 4:
High Sierra (streamliner)
Character B:
Link 5:
![Huh ???](https://www.autopuzzles.com/forum/Smileys/default/huh.gif)
Link 6 (see picture below):
![Huh ???](https://www.autopuzzles.com/forum/Smileys/default/huh.gif)
Link 7:
Honkytonk Man (Joao)
Link 8 (car)
1937 Lincoln Model K convertible sedan (Joao)
Link 9:
Lincoln "greyhound" hood ornament (Tom_I)
Link 10 (vehicle):
A Greyhound bus (Tom_I)
Character C:
Carl Wickman, founder of Greyhound Lines Inc. (Tom_I)
I maybe hadn't given the number of links that can be explained in this puzzle. And without one of them (N°6) it would be hard to solve. Sorry about that. It is shown in the attached picture.