I must say that the aI in racertoom is one of the thigns were it shines. It varies with car classes a bit, but generlaly its my bechnmark in this remark. I have experienced incredible things happening with it, attacking, counter-attacking, -re-counterattacking endlessly, or going on the Nordschleife and fightign it out with the AI door to door and bumper to bumper over half of the lap - a nd no crahsing into me. I come from behind, I blitz beyong it on the one side, it disappears, I have no sight of it ij the mirrors, think its gone away already, and a seocnd later it hisses by on the other side.
It may nbe dependent on driver skill a bit, and I am no alien driver, not even a really fast driver, I focus on being a fighting but safe driver. For my style, the AI in Racveroom is a perfetc match that I prefer to open server any time, and even to what I have tried ( a bit) in closed server racing. It suits my demands and abilities perfectly.
ACC with RR's AI - that would be my dream. AC's and ACC's AI are reliably avoiding crashes, but are too pacifistic. Raceroom's AI is notoriously in a bad mood and evades no fight, also gives up not easily, but is not unfair. But it presses the palyer, if it can. Also, devs said the simulate osme psyhcological factors. If you hunt an aI car and press it very closely, and danc ein its mirrors, you may provoke the "stress" level going up and the AI then may make a mistake.
All my best AI experiences in racing have been done with RR's AI. Its even a little bit erratic, imperfect - just so to avoid getting the idea of dealing with a perfect computer AI, but racing against a human with the usual set of human flaws.
Track Bilsterberg is a secret tip for you to try.
Some touring or GT class of car, old mobiles. Not so much for open wheelers and space interceptors. The flow on that track is remarkable. In Germany it is known as the Nordschleife's little brother.
And Salzburg also has somethign in it. It just keeps you logging laps, you cannot stop.