That is excellent data for those who use or store their PC outdoors.
We have a 2007 2350 with thermal-pane windows and no slideout. We camped a couple times in below freezing temps without hook-ups. The furnace ran only 3 or 4 times during the night. Phoenix USA must be doing a good job at insulating the walls. It's like sleeping in a Thermos bottle. I am so glad the dealer we bought ours from, talked me into the thermal-pane window option. They also make the RV much more quiet. Road & wind noise, and passing semi-trucks are not as loud. We also get better sleep at night. Campsight neighbors, sleeping in tents with fussy children are hardly heard.
Anyone reading this who is considering buying a Phoenix Cruiser, be sure to get the thermal pane window option.