When I was younger, my parents and I traveled from Dallas Texas, to J-ville Arkansas (that's about 6 hours i think?). We had a surburban though when we did it. Since it was such a long drive, after the first hour, (when they calmed down some) we let them out in the back seat with me and my sister. We had a litter box in the car that they could use, and whenever we made stops we took them out on leashes. Just make sure you have fresh drinking water for them. Also, if it's a smaller car...you may not want to let the cat out of the kennal, because you don't want to get in a wreck because of that. However, if one of you took turns sitting in the back with the cat, or taking skeeter out and laying him on that persons lap, i really don't think 8 hoours would be a big problem.
Now adjusting to the new place...that might be another story. But hopefully this helps you realize it's not completly impossible. =P
And our cats came out just fine (this was also after the 8 hour flight from Hawaii to Texas...)