The car and track will be selected by a random number generator just before the race session is created. 

This random selection will take place in the "Race Details" channel in the ISCA discord.  

The random numbers generated will correlate with the car and track row numbers in the following chart below.

No cars or tracks will be repeated until each have been used in that cycle.  If the random number has already been used, a 3rd number will be generated to choose the next unused selection up or down.