I wish the car had a 4th setting. “MPG max”. Let the ICE come on and stay on while operating at 1800-2000rpms in a load range that nets 60mpg. Allowing battery to fluctuate with a larger range 3-25 mile range. If it gets down to 5 miles EV range a driver notification is sent to change to hv hold or hv charge.
I have thought the same thing about a fourth mode but for another reason. The reason that most of us don't like driving in HV mode around town or in hills is because the system is fighting so hard to keep the battery from losing too much charge, which makes for a sometimes annoying amount of noise or lack of power. The only remedy being to switch to EV mode, but then we will use up our EV miles at a fast pace, which in some cases we are trying to preserve. This type of noisy and quirky behavior is understandable in a regular hybrid because they have a very small battery, and it's not good to let it get too low, so they do what they have to do to keep the charge within a certain range. Then again we are basically in the same situation in our cars if we get to 0 EV miles, in which case this type of behavior is understandable because again there aren't really any other options.
But a PHEV has a much bigger battery, and most of the time plenty of battery charge. If we know that our total trip will be within our EV range, then sure we are going to drive in EV mode the whole way. But in cases where we will be driving farther than that, we normally want to decide which portions will be EV and which HV. But that's our only two choices, EV and HV (HV+ typically coming into play later if EV range is getting low). EV mode burns up our range too fast, but HV mode has all of its annoyances. I think a fourth mode would be very useful, maybe simply called PHEV mode, since it's a mode that would be unique to PHEV's. As with regular HV mode it will use the gas engine for primary propulsion and battery power as a supplement, but in PHEV mode it would not try and maintain a particular SOC. It would limit RPM's when accelerating to what is more typical for a standard gas powered car, perhaps even quieter, and use battery charge for the rest of the power needed. Same thing when climbing a hill, try and keep RPM's to what most people are used to on that particular grade, and use battery charge to make up the difference. It would still charge the battery when it can, but only when it can do so without limiting power or making a noticeable amount of additional noise, that will normally be when the car is cruising at a steady speed. But also keep the charge rate low enough to not take the car out of direct drive mode if possible.
This would give a PHEV the unique ability to operate very similar to a gas car in terms of performance and noise, unlike a regular hybrid which requires acceptance of quirky behavior for the "greater good" of better gas mileage. Most of us find HV mode annoying to some degree, some more than others, but we are willing to accept it. But I think there is a larger segment of the population that might warm up more to the idea of a hybrid vehicle if they knew that there is a "higher class" of hybrid vehicle available that drives and sounds like a normal car (even better in some cases), and won't act weird at times or embarrass them in front of their friends. And also be capable of pure EV driving at times, something that a regular hybrid can't do except at low speeds for short distances. And of course have a major impact on gasoline usage, much more than a regular hybrid.
Of course in some scenarios driving in PHEV mode the range will eventually start to get low, and require switching to HV mode to avoid reaching 0 miles, or perhaps some may choose HV+ in some situations. Rather than a notification (which us geeks would like), I think for the general public it would be better if it automatically switches from PHEV mode to regular HV mode at a predetermined EV range. Perhaps that could be customizable in the settings, along with an option for a notification instead of automatically switching modes for those who prefer that. And I think it should still start each trip in EV mode as a default like our cars currently do.
So the three standard driving modes (again HV+ having a different purpose) would be EV, PHEV, and HV modes, since the car can operate in all three, unlike any other type of car. I think that would be pretty cool and add one more advantage to PHEV's.
