Putting out a kart racer is problematic. I got to play an alpha POC from a fairly large studio. It borrowed heavily from Mario Kart. The physics felt right. The challenges felt right, the weapons felt right, and the balance to let underdogs still be competitive seemed great.
In the end it didn't get greenlit. I think in the end a lot of what Mario kart has is standing on the shoulders of their IP. It's undeniably fun It is a great party game, But cart racing isn't for everyone and If racing isn't your thing you can at least still identify with your favorite characters.
If you took Mario kart and replaced all of the characters with Miis, I don't think anybody would want to play it.