Low HV on clarity PHEV

Was your Li ion battery depleted when you drove in HV mode (2 bars on the meter)? From my own experience and some others, there is a big drop in HV gasoline efficiency when the battery is depleted, even factoring in the few miles you might lose in EV range after using a full tank of gas. This is particularly an issue if you need to climb an extended grade. Under that condition, the car cannot draw from the battery to supplement the ICE electric generation, limiting horsepower and racing your gas engine loudly. Even without big grades, the car is super active in HV mode, going all EV for stretches; locking up the clutch in others, and regenerating the battery for a while other times. The actions are much more limited when the battery is depleted because it just doesn't have the flexibility. I always keep at least 60-70% charge in HV mode and I get between 48 - 52 mpg consistently (that's w/o HVAC on, heating and A/C reduces that). Of course, that's between 50 - 65 mph. If you drive higher speeds, mileage drops fast. Nonetheless, Car and Driver got 46 mpg on a 75 mph test loop ( https://www.caranddriver.com/reviews/2018-honda-clarity-plug-in-hybrid-test-review ). That's much better than the Chevy Volt and about the same as the Prius Prime. Both cars are much smaller than the Clarity.

 

We need more info about your driving situation. I get up to 40 mpg at 75-80 mph, which equates to a bit less than 280 miles on a full tank (not counting electricity). We have put about 23,000 miles on ours since Dec, worst tank where I was able to measure mpg was about 35 mpg.

For your 260 mile drive with full charge, how many gallons of gas did it take? The car holds about 7.1 gallons if run totally out. When driving on trips I tend to fill up every 200 miles or so as it is a small tank.