It may just be me but its too easy to create a league, this gives us many either inactive, or low number of cars in these leagues.
Maybe add a points system for all teams and once you reach a level you are then able to create a league, this way you have to work your way through the early stages learning and by the time you can set up a league your a proven runner and less likely to just dissapear.
this will boost activity and make this more of a community game as fuller leagues surely mean more talk and forum posts.
Also rather than just finishing in a position in a legue meaning your no longer considered a rookie perhaps use the same points system to promote teams through the levels.
for me getting promoted to pro before being really ready means a season of last places, but if you got promoted once you hit a points tally would mean your car would at least be semi competitive, you could of course loose points for bad finishes or missed races.