Just one formula 


is that locked diff setups are usually faster on high speed sweepers (like AsNat twisted straights) where maximum power is needed with no loss due to weight balance. Prolly due to unproductive little slip ratio on inner tyre getting all the power left on engine. 


(or just movie editing effect?) to look for wet physics:
Last time one tree won with part of front susp 




(skin modified)
Imagine Danzig in such pose then 