All Hyundai PHEV seem to work that way. It seems there are two philosophies (well, three) among PHEV vehicles. Electric that can be extended with the gas motor (most strongly seen in the BMW i3, and less so the Honda Clarity), primarily a hybrid that can run EV (Prius Prime, Hyundai products), and compliance only (many of the European luxury models).
If you view it as a car that can work as an electric car for most of your daily driving, but has an ICE engine for trips, it would be a major disappointment as it really can't do EV in the winter. However, if you see it as an extended hybrid, that can also run EV when it is warm, it is still a step up from a regular HEV and regular ICE. Generally, while many PHEV get much worse mileage when running hybrid than the HEV version of the same or similar car, Hyundais and Toyotas are generally quite close to the hybrid version of the same car. For the Ioniq PHEV that will be cheaper than the HEV after the IRS tax rebate, the PHEV is an obvious choice. For the Tucson or Santa Fe where you will pay a premium for the PHEV, it might be worth it if you live around here (Maryland) or further south where there are only a few months that you'll have heavy use of the heater, and it may be a no-brainer someplace like Florida or Southern California where you'll rarely use it. However, in a colder climate it probably isn't worth the premium over the regular hybrid.
