The differential window allows you to choose a gear ratio from a scrolling listbox. If the ratio you want to test is not listed, simply type it in to the field. In this model, both tires will receive equal torque. This most closely simulates a stiff clutch limited-slip/posi/sure-grip or spool unit, but will work with an open differential if traction is not a problem.
Drive type will have a significant effect on traction. The all wheel drive model assumes all driving wheels share the same tire diameter and differential ratio.
The polar moments of inertia section allows you to test the effects of lightened wheels, driveshafts, and engine parts on acceleration.