I can definitively answer
I can definitively answer this question for you! You have complete control over the state of charge of the battery. But, if you simply turn the Sportage PHEV on, put it in drive, it will “prioritize” the use of the battery first (until you press down hard enough on the accelerator/go fast enough to switch it into hybrid mode). Since I have made several 300+ miles trips in my Sorento PHEV (which has the same powertrain and battery as the Sportage) I can advise this: DON’T simply put your PHEV into drive and forget about what mode you are in/how you are driving it IF you want to maximize efficiency. Instead, do this: begin your 300+ mile trip by using up say, 5-10 miles of battery range. Save the rest for use en route, switching back to battery for the final 30 miles or so of your trip (assuming you can charge up when you get there; if you can’t charge when you get there, save some of your battery for slower speed driving, perhaps in traffic or side roads but keep at least 5-10 miles of range on the battery until you get to place you can recharge). Why? The answer is simply: by preserving most of the battery for use in slower driving (i.e. 50 MPH or less) you’ll get more EV range. By using up some miles at the start of your trip you’ll have space to recapture some additional range from braking or coasting downhills. By saving enough battery until you know you can charge at the end of your drive, you give the vehicle additional opportunity to run for short periods off the battery when it is in HEV mode. You also save ample “buffer” for going over a tall mountain pass. These things will get you better gas mileage/overall efficiency, I’ve written several articles here on Torque News about my experience following these principles. Let me know if you have more questions!