Riza , Risa , Rica , Rieza , Reiza have there own custom made physics that work hand in glove with Reiza tracks. There are a few Mods that have been made which have great AI racing with them.
I think it is rediculous when you set the AI at 70% and everybody passes you. the AI in almost all the games I have tried in ams is unbeleivable. I also think it is rediculous that this is just a GAME and you should mot be expected to be a master mechanic to set UP?? a car to compete. the ai scale should mean something and not just be in the game for show.
Have you attempted to edit the talent files in the gamedata folder? You find the talent files for the mod you are using, normally they'll be labelled fairly obviously so if it's F1 1971 it'll be something like F171 with the. RCD files found within. Just edit the speed parameters of each driver. Job done. That's the utter beauty of this engine, you can edit and construct the game as you see fit.