@1998Le mans finals Before the November update you could earn CC every day by completing the daily Live Contracts. Within these contracts you had to do some randomly chosen tasks (fly under bridges, earn follower, do skill tests, drive around, win PvP and many more). For each task there was a reward of 1500, 2500 or 5000 CC, depending on the difficulty of the task. You could even roll out a new task once every day if you didn't like the one you got.
Since release of the November update the only way to earn CC is leveling up in the motorpass. If you don't want to unlock the premium version you can earn a maximum of 20k CC during the 2 months season period. If you spend 80k CC you can earn a maximum of 40k CC during the same time. Before the update you could earn at least 90k CC and a maximum of 300k CC in the same time, so the new way in the motor pass is completely #*§$%& and not even near to what we had before.
Only other way is to buy them with real money ... looks like the only thing Ubi still cares is squeezing every single cent out of their customers :(