We've taken Toby on long car trips twice, from Houston to western PA and back. The second trip, we had Chamois so of course she came, too, that year. The trips were two days each way, about 12 hours of driving during the days with potty/stretch stops about every two hours, and overnights in pet-friendly hotels (Red Roof Inn is pretty convenient). Toby LOVES riding in the car, he'll watch out the window, sleep, watch out the window, sleep... Chamois stands and pants for hours before she finally settles down. She doesn't seem particularly stressed, and she's always happy to get back in, but literally hours of panting non-stop before she's finally tired enough to lie down and sleep while the car is in motion. Fortunately, neither is a barker or whiner on rides.
Of course, the car trips probably seemed like nothing after the plane trips that came with our Libya move. On the way there, we flew from Houston to Frankfurt and were delayed so missed our connection. So we had to re-route through Malta and then on to Tripoli, total elapsed time 25 hours (the animals all got a break at the Frankfurt airport kennels during the six-hour layover where they got food, water and potty breaks). On the return trip home a year later, we flew Tripoli to Amsterdam, where they were boarded overnight at the KLM facility, and then on the next day non-stop to Houston. They did great, and I really have to hand it to both airlines (Lufthansa and KLM) in the way they treated the animals - and us, giving us updates and reassurances that they were on board.