Some vehicles only unlock through random prize crates, which also dish out new racing suits for your driver avatar (not to be confused with AI Drivatars), and mods to increase your earnings after races to level up faster. (stuff.tv)
If by any chance you do not have any cryptocurrencies with you, you will have to buy them somewhere else or, if you are patient enough, you can grab random prizes by browsing the site and chatting on the «trollbox». (bitcointradingsites.net)
The challenge is just for fun, but we do have some random prizes to reward during the month! (theclothdiaperwhisperer.com)