iRacing has chassis flex and I think AMS1 doesn’t. BTW: I believe AMS2 (and Project Cars 1&2 ) has it too. Still it’s possible that AMS1 F. Vee is the most realistic. I think realism is more dependent on how accurate car values/parameters are fed into the mod. For instance Madness engine is very advanced, simulates many aspects that rF2 engine doesn’t, but still handling varies depending on a car.