That was I-16 and I-75 too. I filled up in northern Chattanooga and somehow I timed the traffic perfectly to where I didn't have to budge off of the cruise control at all the whole way. I was very lucky to get that kind of mileage. The stars and planets must have been perfectly in line because I've only broke 20 mpg 2 times since then.

 

I generally beat cruise control for mileage. Actually, I haven't been in a car or truck yet I couldn't beat the cruise. My 04 SCrew with a 4.6 was getting me 22-24.5 hiway. I just finished some mods for fuel mileage and so far, it looks like I might squeeze into the 26.0+ mpg range. I haven't had the time to put it on just hiway driving since I worked on it but the town mileage is going to be well over 20 and probably over 24 mpgs. I've only put 160 miles on it and I'm still above 3/4 tank which is quite a bit over what the truck normally gives at the same gauge mark. I'll know more next week. And yes, all of my mods are emissions complaint.

 

what is your favorite rpm for accomplishing that amazing number, I must know
What size/brand tires too?