I agree with another poster re: going slower. I've found that at speeds above 65mph, the mileage drops precipitously. On a flat road with temps in the 60's or better I can get into the mid 50's with cruise and no traffic in front of me altering the speed. At 70+ and/or cooler temps the mileage goes down below 40mpg. Another thing to check, is your tires when they are cold
. Hwy driving will warm them and increase the pressures which will increase the MPG's.
Interesting battery drain; the other night when leaving church on a cold rainy night, I used the rear window defroster for the 1st time to clear the fogginess. I noticed at a stop light there was a low orange glow on the power meter needle at the lower 'resting' place. When the light changed and I gave it power, the glow started to follow the meter needle up then diminished and didn't come back on. Has anyone else seen this? My guess was that with the heater, wipers, headlights and rear defroster on together, the load might have been more than the system liked while stopped and the 'ICE' wasn't running.
I don't know how one gets 55mpg on the highway. I just did a test. Totally flat and straight highway, no wind,80degrees 120miles, cruise control, HV mode, 74 mph and I got 38.56 mpg