When used to de-ice driveway: "Kitty litter ... is nothing but glorified clay. While it will help with traction, it won’t actually melt snow (chemically speaking). It’ll just absorb it, leaving you with gobs of wet clay." The article didn't say if it was used or unused.
However:
"Did you know that of the 11 essential items to keep in your winter car kit, kitty litter is one of the top 3? If you find yourself stuck in snowy slush, non-clumping cat litter can be a lifesaver (or at least a timesaver). Pour it in the path of your wheels to help get traction.
And, as anyone who’s ever lifted a bag of cat litter knows, it’s really heavy, so if you keep it in the trunk, it’ll add weight to the rear of your vehicle, which can also improve traction."
Cat litter for this, I assume, is unused.