Apart from 30kg of weight ,pit limiter and headlights I see no difference in performance between the 2019 and the ,2020 & 2021 stock cars. I see no difference between 2020 & 2021 so why are they in different classes? Some livery changes yes but it confuses me to have all these same cars in different classes.
While 2019 and 2020 are the same car (just different season and ski pack) the 2021 one is a different car, different specs and weight distribution, etc etc.
Slight correction: 2019 is the older spec. 2020/21 are the different cars of the new SC Brasil spec. They have less aero (about 50% less), slightly shorter wheelbase, harder tire compound and aren't so wide. They're about 3-4s slower than the 2019 cars on a 1:30min. Laptime base.
No because you'd want to run the 2020 season in a Championship without the 2021 liveries and drivers being mixed in and vice versa. There also could be little differences between the two seasons, but I don't know that.
The car is the same spec, but the liveries are different. You can of course mix 2020 and 2021 in a multiclass scenario and receive same performace, but it's not really necessary.
