Depending on your tank fill technique, you have some miles left at zero range. I've yet to run out of gas, but I have several times been a couple miles (7 miles was the most) below zero and filled the tank to its rated capacity, in the case of my HEV, 11.9 gallons. I fill to the brim, so I still have whatever is in the fill tube above the rated capacity, perhaps 15 miles? I'll find out some day. In addition to that, depending on the SOC, you might be able to limp 6 miles or more past that on EV only. Perhaps even more, as there is a hidden additional 20% that serves as a buffer, both to avoid damage from getting really low, and to disguise ordinary battery degradation from affecting your displayed EV capacity and range. As an additional safety, I suspect the range remaining is very conservative, pushing you to fill up before absolutely necessary.
At some point, I will run out of gas and limp into a station. My nerve and opportunity hasn't allowed that yet. Then I will know for sure how big the safety margin is when remaining range is zero.
2018 Kia LX HEV Metal Stream with Advanced Tech