Hi, we have a FRED ordered--should get it around Nov 10, and have tried to find information about them, but there just aren't that many people on the forums that own or have owned them, it seems. Search this forum--there are some threads addressing this, and also this thread at the GulfStream forum was started by the owner of a new Crescendo FRED. They haven't posted since their first couple of trips, but they got 10-11.6 mpg when not towing: http://www.gsowners.com/viewtopic.php?t=376
Once we get ours, I'll post our mileage and anything else relevant!
Good luck in your search!
Jill