you can bring home an upper respitory infection to your cats - basically the
common cold - and distemper.. everything else the cats have really needs to
be a cat to cat contact in order to pass it along.  The exposure has to be
extensive though.. more along the lines of you patting or cuddling the cats,
then coming home with out washing your hands or changing your clothes, then
patting and cuddling your own cats.  If your cats are in good health, and
are vaccinated against distemper, and you wash your hands on a regular
basis.. then your fine.

Kudos to your cat lady friend.. she has my appreciation.  She's doing a
wonderful thing.

Most germs aren't going to survive long at all in a car. Believe me, I handle
cats with practically every disease common to cats at the shelter, and mine
have never gotten sick from it. I *did* however, bring home ringworm spores on
my clothing and Frank caught it once. But honestly, casual contact like *you*
riding in a car, without the cats, I don't think puts your cats at much risk.
My heartfelt appreciation goes to your friend. It's not everybody who will take
the responsibility for cats that aren't "nice and healthy." Someone has to do
it.
Sherry

I shouldn't have thought so. I have friends with two cats who are
FeLV/FIV positive and the vet told me the chances of transferring it on
my clothes was next to zero - even if the cats lived together the only
likely transmission was via bite or scratch wounds.