Board Thread:Questions and Answers/@comment-27398588-20151214150908/@comment-104.36.11.70-20151214164825

It could be for multiple reasons, one of which is the V8 card is not needed yet. The 8C only needs V8 engine cards for the fifth and final pro kit formula. Stages 1-4 for the 8C only needs C class cards and early/initial tech.

Another reason is that you could be having a Forced Induction V8 by mistake. FI V8's are only needed for B-S class cars. To differentiate both V8's, the regular V8 has a white background on its card and is considered to be of common rarity, the FI version has an orange background and is of legendary rarity.

Alternatively, you could be lacking in either credits or pro kit cards. For the kit cards, buying the super racer kit box for 18,000 credits every 8 hours should help. For credit grinding, check this page to see what races other players grind on.

Your internet connection could be another factor, playing offline or having a slow/weak connection will prevent you from accessing the pro kit upgrades. If the game can load up this week's multiplayer events, it should also be able to allow pro kits and the microtransactions.

Also check out the page on pro kits for more details and info.