Never had this issue in my wife's mostly city driven Prius C. When in Anchorage, the car may get short tripped for many weeks straight in the dead of winter. We do plug it in whenever possible overnight (but that doesn't bring the car up to temperature to take care of all condensation). The TGMO 0w20 does it's job very well and the coolant system in the Prius is clearly well engineered to save waste heat. Regardless of what you drive, it needs to get up to full operating temperature. If she only drives a couple miles and back and never highway, she needs a full electric.