The Gen IV saw slower sales due to the same economic factors that saw sales of virtually all " Want " cars decline. No one needed a Viper, Vette, Porsche,Lambo,Mercedes, etc. and sales were down Worldwide. Looks are always subjective, but I know having had 3 Gen IIs, three Gen IIIs, and now my ACR, at local car shows the Gen IV ACR gets more looks , questions , etc. than any of the other Vipers I have owned. Doesn't even matter if it is my favorite, the reactions tell the story.
Folks usually think the car they own is the best one out there, and that is human nature. The reality is interesting , as we get 4 to 5 times more requests for Gen III and Gen IV cars than Gen IIs. People seem to love Vipers across the spectrum, but no one is foolish enough not to believe everyone will have their specific favorites. I enjoy the entire evolutionary line, but I too have my favorite, though like the first girl you kissed, there are soft spots for all of them in my heart.