Important Disclaimer:
I was very, very close to disqualifying the Ferrari 641 from this competition. There is a rule to this competition which, so far, has not needed to be invoked; no car can win more than one decade. Given that the 1990 641 is a tracing paper evolution of the 1989 640, and that the 640 did win the 1980s decade, it would be somewhat uninteresting for its derivative to win the 1990s decade too.
However, instead of running this like a dictatorship, I decided to allow it and I will put my faith in you voters instead.