Solved

What is with car numbers?

I'm not sure if it's a bug or not, or maybe I just don't understand it. One race, my cars are #'s 10 and 11, the next they are 5 and 6, the next they are some other numbers. Why are the numbers always changing? And why can't we pick which #'s they are?

Is that roughly the position they were in that race? There are options to view the car number or the car position. If you have chosen to view by car number it should remain the same for the length of your season.

They do change sometimes if people join or leave the league you're in. They shouldn't change otherwise but I have to admit I didn't pay attention to them lately. There are still some other problems with those numbers like the championship winning team mostly gets some higher numbers and someone else, often the 3rd or 4th in the championship, the 1 & 2. Those things were a bit lower on the priority list for the Devs until the Apps are out but hopefully get addressed soonish now once the last emerging quirks in the Apps are ironed out, those servers are back to running normally and the Devs got some deserved rest.

there is a bug involved but, there are more important things going on at the moment.
they are working hard trying the game to be stable, so we have to wait a little more for this kind of things.

cheers