Hi Robin,
 
You don't mention where you are now and where you're traveling to... This
can be significant depending on the temperature.  As you probably know,
ferrets don't react well to heat and a long car trip can mean a lot of
heat.  I've found that for some reason they don't drink a lot of water
while the car is moving (maybe because they sleep more) and they can
become dehydrated.  Make sure they have plenty of fresh water (stop at
least every hour or couple of hours to change it and to make sure they
drink it).  If the sun is hitting their cage, cover the top with a towel
but make sure they have plenty of ventilation.  If you have the AC on is
not enough for them.  They need air so don't stack suitcases against the
cage.  You may want to consider buying on of those pet fans that you can
hook up to the cigarette lighter.
 
Ferrets react differently to car trips.  We have 4 and we constantly
travel with them.  Two of them go to sleep as soon as we start the car,
but the other two like to look out the window (just like dogs).
 
When we travel during the summer, we stop every hour or so and we give
them fresh water and even sprinkle their coats, so they remain fresh.
Also, we let them out of their cage every time we stop for
gas/food/bathroom breaks, etc.  and let them roam all over the car.  We
take their large cage (3 stories) with us and put it in the back of our
blazer and put the back seat down so we can watch them all the time and
see how they are doing (maybe I get a little paranoid, but we like to
make sure they are breathing normally).
 
It is fun to take them with us, and everywhere we go they draw a lot of
attention.  They like to travel, in particular because almost every time
we go somewhere is to go visit their "grandma", who just spoils them all
the time.  I think they love it.
 
Good luck!  Have a safe trip.
 
Joe
[Posted in FML issue 3738]