In the summer my 2017 Volt will get about 38-40 MPG at 75 MPH. In the winter with the additional drag due to the cold combined with the power requirements to run the blower I can easily see 35 MPG. To improve your MPG, turn the HVAC to Eco once the cabin gets to where you want it, make sure your tires are running between 36 and 40 PSI before you start out, and clear all the ice and snow off the exterior.