Hi,
I agree, its much better the Grand Prix Circuit C=64 Version.
Another Better versions in C=64:
California Games, Mision Imposible, Tenange Mutant Hero Turtles, Defender of the Crown, Creatures, Sky or Die, and more..
i can´t remember but is very long the list of the games made for C=64 and later launch in Amiga, and the Amiga Version is not impresive, you know, i expected more quality of thats games for Amiga, and the games was more low of the C=64 version. And not only C=64 vs Amiga version. Many C=64 games version was better of the NES, Sega, etc versions..
Anyway that part of the C=64 games world, and another excelents games was developed in Amiga, and the Amiga Versions was the best version in all the plataforms game launched.
Regards..