Real world MPG Ford V10, what gear and cruising speed ?

THANK YOU for saying you won't slow down. Seriously, thank you. Moving with traffic is imperative. Driving slow in any type of RV makes you a hazard, and that's not a good thing.

I get tired of seeing selfish statements such as "I'll drive 50 or 55, and if anybody doesn't like it they can pass me". Really? How considerate :R

If I feel like making a more leisurely drive, or if I'm that concerned with my fuel economy (yeah, right!), I find US and state highways to be wonderful, and use them often.