I think GT4 is more arcade than simulation.. I just read you wrote about driving aids - in RBR only driving aid is automatic/semiautomatic gearbox!!!!!!!!!
I've never played GT4 sorry mate I don't know.. But I played all racing/rally/simulation/arcade games on PC since 1990, I can say only - this game has few bugs ie. you have to install patches to avoid crashing the game but as simulator it's definitely best one. I's really only for patient gamers,btw - our oldest community driver I know personally is 49 years old.. One more thing - if you have some previous experience in real rally or similar motorsport it will be very useful because without real life skills it's impossible to set up a car properly,this includes active differential mapping,complete geometry setup - toe,camber,caster,springs,3 way shocks,tyre pressures etc.,same as on real car.
Out of curiosity, how does it compare to Gran Turismo 4 with all the driving aids turned off? (On asphault I mean, the rally part of GT4 seems a little weak to me)
Otherwise - for fun/drift try games like Live For Speed - LFS or GTR/GTR2 maybe those ones are more fun/drift whataf*** oriented although they keep some level of simulation,they are better for fun,worse for serious competition. YES - RBR is competition,always,you compete against clock,compete against others but mainly against Yourself,this game will kill your mental health :-)