Just got back from a 2,417 roundtrip from North Myrtle Beach, SC (hometown) to Beaumont, TX (son's home) in our 2017 Jayco Precept UL31 and back. We went down I-95 to Jacksonville and then I-10 to Beaumont to avoid Atlanta. We were pulling our 2018 Sonic. First long trip for us. We averaged 10.3 mpg for the trip!!! Not bad for a motorhome with Ford V10 on F-53 chassis. Rarely got over 60 mph as the limit on the Sonic is 65 mph.
I'm the one usually in the left lane leading the pack. Due to the limit on the Sonic, I had to go slower but after a little bit, I found I like being in the slow lane. Set my cruise and rarely had to slow down for anyone!! So if you see RVs in the right lane going slower than the posted speed limit, it could be that they are limited in their speed or going slow to get better gas mileage. Now, where to next for us???