For Your Info: Anyone contemplating a trip from the Midwest to Yellowstone here is some info: Left Apr 13, 2008 arrived May 4, 2008. Fuel from Dayton, OH to Cody WY: $750 at an average of 10 miles/gal. Total 1900 miles. Average price for diesel $4.10/gal. Higher now. RV Space/night: Average $32/night.