Look at a C-4 carefully, and you will see that it is one of the most faithful at keeping so many touches of earlier generation cars within it's, at the time, revolutionary re-design.
Casual lookers may get the taillights, but miss the many other tributes tha were incorporated into the design.
Just as the C-3 was a game changer form the previous generation, the C-4 was even more so, and yes the C-5 was just as much also, but each kept some special similarities.
C-6, more evolutionary, than revolutionary.
The C-7 simply looks like it came from another planet, but again, look carefully and the tributes are there as well.
C-4's likely will find more appeal as they age.
Marty