Board Thread:Game Discussion/@comment-31295789-20170506001114/@comment-31374292-20170506152309

No way to really cheap solution. I already have all the first level gold upgrades on these cars for winning them but still have to pay around 200 gold for each car's further upgrades (with the discount) if I want to finish their series. This way I can get back 300 gold from sponsors and some small change for the two related series' completion, don't know the exact numbers (you can visit the relevant wiki pages). If I am smart, I can earn further 100 gold by driving myself to group B with one of them in wttt. Nevertheless I guess I will use this discount, these cars are unique and fun.

If you start the gold upgrades from scratch now, the costs will be higher, the rewards will be the same.