It's a base 2016 XC70 T5 five-cylinder, no Polestar - I use premium gas - on the highway at 64 mph, the average hovered between 33.8 mpg and 34 mpg, was at Hartford at 34 mpg average. I am very impressed with that, did not think it would be so high, but then I deliberately drove 1 mile below the speed limit to see what would happen.
On the highway, I generally do 75 to 80 (like everybody else), and get lots of 26.6, 26.8, and the occasional 27 mpg.
i live in a semi-rural, hilly area, and driving around town and on back roads I average 20-21, a lot of 20.6 and 20.3 and so on.
Since I am not on the highway that often, the overall has been around 21-22.