Fuel consumption

Im new here, I havent had my CDL even a week. Ive been wondering What a fl70 freightliner would get on fuel mileage. Without a trailer I mean. I know thats a hard question because there so many factors involved. So Ill just say a fl70/ or a fl60 with a detroit and 10 speed tranny and no trailer. Just the sleeper on back. Im just trying to get an Idea, Because a freind of mine has made me an offer I cant refuse hardly. However this truck is 1500 miles from me. Im not about to venture out on my own! I just thought maybe Id haul hay with it and use it for personal use. When I go to work Ill drive for a company in their truck. This truck will be a toy, For pulling my camper sometimes , and playing around on my farm. Im looking for just a Ball park guess.

 

Thats not bad, considering there are some dually pickups that dont do much better once you add a truck camper.