Board Thread:Game Discussion/@comment-27095714-20160809055110/@comment-89.121.200.106-20160809080950

Very interesting... The FXX K exclusive series has 18, 30, 40 and 64 gold for series completion percentages, for a total of 152   gold. I fully upgraded it during the 25% discount, and now I am goint to get some of that gold back.

Also, the R34 has a total 41 gold for completion rewards, and it only costs 3 gold to fully upgrade (+38).

I do not have the other ones fully upgraded, but I expect reasonable return of investment for low and medium PR cars.