Been away for a while, but I appreciate the convo going on here. Thanks USB for checking it out. You are probably right though, that the rate of fuel usage is extremely low during this time.
Could this simply be the BMS revising the SoC downward as it gets a better reading on the battery voltage at low or no load. As SoC goes down so would the estimated range. Maybe the range/SoC calculations were a little off do to a particular diving pattern. Also the Rx450h will idle the ICE during parked warm up and or when heat is requested and the ICE will be the only thing powered up. No electricity at all until you draw down the HV battery SoC because of the use of system computers, lights, heated seats, power adapters, ect ect.