Average 60-65 mpg in summer? What do you get in winter?

I have a 2015 Two Liftback that I bought in April 2015. There is NO such thing as average fuel economy. Every tank is different. Conditions change , even in the space of one tank ( 7-11 days for me). I do keep very complete records , but for now all I will say is a summertime high of 65 MPG (actual) for one tank and a wintertime low of 52( actual). My commute is 34 miles ( 24 highway,10 suburban). All the highway is 55 PSL ( recently up to 60 ). Highway , I DWL from 54-62 MPG (55 when road is flat). I "can" get 60 + MPG on highway , but only if conditions ( wind and temp ) are optimal.
Of course , this car's first winter is far from over ; I could have a worse tank. I'm not using grille blocking or a block heater. I do have a Scangauge that I use to monitor coolant temp. I don't pull any heat from the engine until I am on the highway , unless of course , I need to defrost for safety reasons. I am now keeping the car in the garage , so I rarely need to do that.

 

I haven't owned my Prius in a summer yet but am getting between 44-48 mpg in our Minnesota winter driving mostly on freeways.

 

Come summertime your MPG should improve. YMMV