I am still on my first tank of gas from the dealer, and I have about 2200 miles on it. I just went on a road trip and my average MPG went from 230mpg to 204.9mpg. I drive often in EV mode, but I am surprised when the engine kicks on sometimes in this mode. Popping the car into L seems to make this happen, especially with the HVB nearly full.
When I turn on the car and place it into EV Later mode, it indicates that the battery is 95% charged, versus the 100% charge that the car otherwise indicates. I believe someone indicated 13-93% SOC which would seem pretty accurate.
I bought the car in August. I have an almost exactly 30 mile trip to work, and would make it to work on the battery in the summer fairly easily. Now that the temperatures have fallen, I find that 25 miles is about I am getting, so I am putting it into EV Later mode for hills and areas that I have to accelerate. For this reason I picked 27 miles, which is about my average.
I am about to fill the tank for the first time, and I am leaning towards Premium fuel which is recommended in the manual.