The street you intend to take your long rental truck + car carrier carrying precious car will be closed. There will be police everywhere. You will not have time to stop and look at what might be some kind of awesome police showdown involving guns and hostages and demands. Instead you will be annoyed and inconvenienced and have to almost hit several people's parked cars navigating narrow side streets.
The first CD you put in the truck's CD player will be swallowed. It will refuse to play or come out.
You may appreciate how scenic Oregon can be now that you're leaving it.
Going through an odd section of Eastern Oregon you may encounter an excess of available radio stations, considering you are nowhere near anything resembling civilization. One of these stations may or may not play nothing but Black Sabbath.
Getting to Idaho will take longer than you expected.
Once you get there, you will wish it had taken even longer.
Boise will look like 180 thousand people the world would be surprised to find exist.
You will discover Idaho is on Mountain time, even though Nevada directly south of it is on Pacific.
While stopping to relieve yourself and trade places with your drive partner, your wallet will fall out of your pocket. You won't notice. One mile later you will. Freaking out will occur. Swearing, too, regardless of your current stance on profanity.
You will drive several miles to the nearest exit. Then several miles back. Then another few miles to the place where your wallet could likely possibly be.
It'll be dark. You'll try to use the truck's headlights as a flashlight. You will eventually find the wallet, strewn at an odd angle that indicates you probably ran it over with your own car, stupid. Your ID will have fallen out. You will never find it.
Finding a place to sleep in Twin Falls will be harder than you'd think. One place will be booked. Another will have only their two most expensive rooms available. Finally, you'll settle on the third place and their only room, the so-called jacuzzi room. Sadly, this jacuzzi will not be shaped like a big heart.
You'll fall asleep at 3am, hoping tomorrow will be a shorter, easier, less stressful leg of the journey. You'll be wrong.