SWIFT trucks not so fast
I've noticed that Swift trucks tend to be running around 65. A truck driver told me they are governed to 64 mph. This avoids the speed changes up and down most hills.
Drafting a couple of seconds behind a truck can save a lot of gas. From riding a motorcycle, I can feel that it's not too much different closer, and it's not worth the safety factor.
If a semi is not available, the ones with the most draft are SUV's if you can find one going a reasonable speed and then pickups. These two have even more air disturbance than Semi's. I don't know if that's good or bad for the mpg, but it's worth checking out.