couple things you could do
• campaign mode with micropayments every ten levels (2 tiers - free to play = small micropsyments, pay to play slightly higher micropayments at a higher difficulty)
• car rarity based on win % and parts
• make buying a car and/or parts through bsv only, and only through a store not peer to peer
• base car is an nft, every new upgrade burns the previous nft and mints a new one