Board Thread:Game Discussion/@comment-176.221.120.73-20170621095251/@comment-30967537-20170621113705

To be clear, the final PR for the EK series is 95 for which any of the LMP1 cars will need Gold upgrades, you can't unlock the event with R$-only upgrades. If you don't have any of the cars and have to buy them then the Audi is the cheapest option to buy and upgrade, if you already have some of the cars then it depends on the upgrade costs. The Porsche is the cheapest to upgrade, then the Audi and finally the Toyota. Check the official Upgrade Strategy page or my Upgrade Strategy blog for all car-series upgrade options. Good luck.