We took our kit by car to the vet to get "done" about two months ago. On the way there it shat itself & on the way back it pee'd. Long haired cat in loose shat horror - yuk - but the vet took care of that (cat is a little shorter-haired in places).
We have found no solution for the pee-smell. We are trying to dispell it with unsympathetic magic though - crossing our eyes & quoting "damn cats" whenever entering said vehicle.
Not worked yet.....