This is so difficult to translate into English! Competitive driving is more of a sport than a hobby, but it's not something you 'play,' it's something you 'do,' but the verb really is 'drive' or 'compete' - very complex. Since the meaning of the sentence doesn't have a direct English translation I can see why Duo is struggling to define all the versions. "Joni drives in rallies... as a hobby," "Joni competes in rallies... as a hobby" should be added too. The 'hobby' ending is assumed without needing to be said in English through the habitual nature of the simple present verb.