I've done half of one. Getting into the event at the end of the day has long long traffic jams. The variety of cars, trucks, rat rods and anything you can imagine is mind boggling. I personally enjoyed the daily routes, people would line the streets in towns, out of towns, overpasses, everywhere, its one huge parade. Imagine pulling into a small town fuel stop 7-11 and its covered with cars. Parked at the pumps will be a Hellcat, a blown 57 chevy, a big block camaro, a couple of rat rods, a Boss Mustang, its cool, not a Prius insight.
The hotels at night are just as overwhelming with cars, Shelby's, Fairlanes, Chargers, ACR Viper literally anything. I saw several full on custom build cars that became auction and magazine feature cars, impeccable craftsmanship, whatever you can and can not imagine.
There are several types of tour attendees, a lot of people ditch the planned route and get to the event as quickly as possible, typically they are doing the entire run and are trying to win prizes. People like me who drove the planned route and the day trippers, whom I feel caused the majority of the traffic problems.
My carbureted 337 stroker with a 4 speed averaged 26 mpg which surprised me.