Make a new fast circuit. A long one. And make it Monza
Challenges. The slalom course but where you drive straight, do the u-turn and drive straight back. Tug of war? Two cars chained up pulling on each other.
Jumps! Loop the loop!Bond style bridge barrel roll wotsits!On a marginally less stupid theme...Ice starts (full car or rear wheels only or even one side only) leading on to normalish tracksMulti-lap where conditions change, i.e rain on 2nd lap or dries up or rapid snow thaw to wet etc.