Good stuff! After a little practice and learning the racing lines, I was able to consistently beat the bots. That is to say they had a good level of challenge that required me to practice (around 5-10 races).
I liked the variance in how many turns actually forced you to engage your drift to take them smoothly, I think it made the drift-required turns feel a little tighter and more engaging.
If you fall behind, catching up is really difficult, so maybe some comeback mechanic could be nice? Good racing lines are effectively the only way to close that gap, but not many people would know about that...