Board Thread:Game Discussion/@comment-93.103.154.255-20160502115651/@comment-27048832-20160502120616

I don't know about the 2013 / 14 cars I was lucky & Motorfiesta 1 unlocked upon completion of RtLM

The 2015 with R$ upgrades will get through Racing Spirit to unlock McLaren Generations

That's all the info I can give, others will have more informed advice about the 13 /14 cars :)