Board Thread:Game Discussion/@comment-112.210.235.18-20170606121930/@comment-27544091-20170609155655

Upgrading to series completion - PR 55 - costs 648 x 3 = 1944 gold.

Considering that you won them during their release update, you probably have invested around 200 gold in each of them.

(1944 - 200 x 3) / 2 = 672 gold - estimated cost to PR 55 for all 3 cars.

Deduct the 300 sponsorship rewards from FE: Experience and the final rewards from both series (30 + 31) and the net cost of completing the 2 series will be around 300 gold.

If you got the cars for free, math is 1944 / 2 - 361 = 611.

Personally, I won the cars during their release update, with ~300 gold upgrades on the renault and ~200 on each of the other 2. I have FU'd all of them during the previous sale.