A few days ago I made a trip south on US101 in California from Arcata to San Luis Obispo in the 2012 EarthRoamer. Here is the message center for the trip.
I confirmed the actual distance to be within one mile of the reading shown on the message center at 526. I filled up the tanks and they took 42.9 gallons versus the message center reading of 42.8 gallons. So over the 526 mile trip the 2012 EarthRoamer fuel milage was an amazing 12.3 mpg. The enroute time of 10:51 included about 40 minutes for a lunch break with the engine idling and some stop and go traffic in Oakland. During the trip the ER had one regen.
Great mileage for a 17,000 lb rig.
2014 F550 EarthRoamer XV-LTS