My Chrysler Pacifica Hybrid shows EV and HV miles driven but it’s not entirely accurate. Let’s say you’ve charged you battery up completely and you take a long trip in EV mode. After some miles the battery is exhausted and the vehicle switches over to hybrid mode. At this point the EV miles should be set in stone at least until the next time you recharge. But it doesn’t work that way. Every time the engine shuts off in hybrid mode those miles are counted as EV miles, like when I’m coasting down the other side of a mountain I just climbed. But in reality those aren’t technically EV miles in my opinion. The only reason I could coast down the other side of the mountain is because the engine was running in HV mode coming up the mountain in the first place. Technically, in my opinion, the miles coasting down the other side should still be counted as HV miles. So if the vehicle doesn’t even know how to categorize the miles driven, how could it correctly calculate the actual mpg? Just an observation.
I agree it should only count EV miles when you are in EV mode. Think about a situation where someone is unable to charge and so they always drive in HV mode. From what you are describing about the Pacifica it sounds like even for those people it will show some EV miles driven, if it counts whenever the engine is off. You don't even need to be going downhill for that to happen, I sometimes see the EV light on my Clarity come on briefly while I am cruising at a steady speed on a flat road.
Then again even if they did it the way that we think it should work, what about when someone uses HV Charge? On the Clarity you can easily store up 25 miles or so of EV, of course using gasoline to do it. Then later you switch to EV mode. So it will record 25 miles of EV, but really those EV miles came from gasoline not the grid.
In theory with some fancy software algorithms it could keep track of kWh that came from the grid, kWh that came from regenerative braking, and kWh that came from the ICE generator, and keep those numbers in separate "buckets". Then somehow allocate those as the car is driven, either using a FIFO method (first in, in first out), or maybe a prioritized method (grid first, then regen, then gas generated). And of course it has to separate out miles driven while in gear mode (engine direct drive) all of which will get allocated to HV. And if you shut off the car with some charge left it has to continue to store the kWh values in each of the buckets, to be allocated on your next drive.
I don't see them going to this amount of trouble, I mean how many more cars will they sell by doing this? So unless or until they have something that sophisticated, probably the best way to come up with a realistic number that is meaningful is to simply calculate based on gas purchases, which gives a reasonable estimate of miles driven on gas. If someone is interested in EV miles then just subtract gas miles from total miles.
