How to get the "Unicorn" cars. (In Forza Motorsport 6)

Hi everybody, I recently know about the unicorns in FM6, and i was wondering, how do I get the cars, It will be like FM4?, forums participations,or making designs or participating in monthly events?
Please answer.

The answer is in your question
Community participation in certain events

Current opportunity is in the Lambo events which if you havent already participated in you will have missed out on it this time around