If your not willing to spend real cash don't play – Racing Rivals Review

This game is really unplayable without spending real money. There isn't enough activities to generate coins or gems to make the game entertaining. Most of the time it's playing the same level over and over again losing and earning 200 coins for good shifting when a lot of the upgrades cost 3000+ coins and require usually two or more upgrades to beat the level.
Review by Dwheet on Racing Rivals.