I've only had the tires for a week, although 4 of those 7 days were my drive to Ohio and back. On my trip to Ohio, in which the mpg in HV mode as measured by actual mileage and gasoline use and was not much affected by using the heater, I got on each tank of gasoline 38.8 mpg, 39.5 mpg, 40.8 mpg, and 42.3 mpg. On the drive back from the Ohio border to Wytheville, VA the temperature in the twenties most of the way and there was a significant increase in elevation. I got only 32.1 mpg. The next two fill ups resulted in 41.3 mpg and 41.0 mpg. All my driving was as much as possible about 5 miles an hour over the posted speed limit. Compared with my previous drives to Ohio on the OEM Michelin Primacy MXM4 tires, both made during warm weather, the mpg was either the same or only very slightly less.
As to EV only range, I haven't had them long enough to make a definitive determination. In the 3.5 years that I have owned my Clarity, it has lost about 10 to 15% of its original EV range. After I got the new tires last week and before my trip, I had the alignment checked, corrected (minor out of alignment) and the brake fluid changed.
Based on my two previous long drives to Ohio and back, I believe that the new tires provide at least 95% of the same mpg as the OEM Michelins. Thus in a situation in which I would get 50 miles on a charge, I expect between 47 and 50 miles with the new tires. Today I only got 42 miles, but I drove through rain going south and then on the way home north on A1A I was driving into a steady 7 to 10 mph headwind.