The A car is affected most due to lower drag and rear downforce. It's one of the reasons why pulling on the rear quarter works so well in real life as it sends air up and over the rear of the front car rather than around it creating a huge low pressure void on the rear corner of the car being passed.
Te other cars are less aero with larger spoilers so airflow is already pretty badly disrupted
Your guess, real or from the iR forum, because others say so? This is not meant to question your view, just a question.