I think 10000 is fine if you can add some variety and events on the way. Maybe a few traffic lights? or some dialogue for what the player is thinking?
> Not exactly: you can ride under trees, but the render sorting works wrong here so the car is drawn on top of the tree, but you can't drive through the bottom of the tree
Ah okay, so you probably ran out of time by the time you noticed. Yes, the collider is fine.