I believe that one off Packard fastback was created by Peter Portugal who also did this one off woody. Having seen that car is is truly a work of art. Cleverly uses the tailgate of a 1949 Dodge or Desoto wagon which contains a spare tire.
The model or the real Buick? This is a Franklin Mint one and it has an opening hood showing the green "nail head" V8, other engine bay items plus opening doors. Notice the Buick is the only one of the three that did not have the wrap around windscreen that was just coming into style.