They'll do fine. Here are some precautions to take:
-- Don't hang the water bottle in the cage. Most will leak while in a moving car. Feed them small amounts of very wet veggies frequently during the day, and stop every couple of hours to offer them water. But don't be surprised if they don't drink.
-- You can transport them in a fairly large dog cage or in a large plastic container (no lid).
-- Keep something in the car to cover the cage with to keep the sun off of them -- they can get overheated very easily.
-- Take a floor-time pen for the motel so that they have some space to run around. You can just put an old blanket down for them, or towels with fleece.
-- I put the cage in the car where the pigs and the people can see and interact with each other. If there are two people, I put it right behind the front seats, with the grid door facing us. If I have them alone, I put the cage in the front seat with the door facing me.
-- Put a cardboard hidey in the cage, something like a soda pop box with the bottom cut out. You can even cut most of the front off -- it won't matter if it's open. It's just something immediately over their heads so they don't feel so exposed and vulnerable.