Join Date: Mar 2018
Location: Toledo, Ohio USA
I have the plug in Ioniq, not the electric, so maybe my winter efficiency experience is not what you are looking for. But I did learn a lot this winter about the phev efficiency.
I got the car last year and spent the spring, summer and fall driving short trips to work on battery and taking long weekend trips on battery/gas. My average fuel efficiency was always high, between 300 - 500 mpg US. I expected that during the winter my mpg would go up because I wouldn't be taking the long weekend trips. Boy, that is not what happened at all.
When it got cold I turned the heat on with the temp set to about 70 F. This caused my displayed average mpg to plummet from my pristine highs. After a month or so it had fallen all the way to 100 mpg US (120 mpg UK). I dialed the temp setting down to 65 F (18 C) and that helped. The engine seemed to just idle as needed for heat this way and my displayed mpg held steady as I drove around town in EV mode. Later I realized that my displayed average mpg acts more like a rolling average instead of a cumulative average. So that might explain why it dropped so fast.
A few months ago I read that consumer grade lithium ion batteries can be damaged if recharged when the temp is below freezing. Unlike the EV Ioniq, my phev Ioniq does not have pre-heating when plugged in or a battery heater, and I don't have a garage. I do charge at a slow rate (especially compared to an EV) which helps protect the battery. And the car/battery come with a long warranty in the US so I shouldn't have to worry. But the warranty in Canada is shorter so I figure cold weather affects are real. I plan to keep this car for a long time, so when the outside temp got really cold I decided to drive in hev mode. This caused my displayed mpg to drop even more, now down to 50 mpg US (60 mpg UK). (Though my average on Fuelly is still 150 mpg). This last week the temps outside have been as low as -13 F (-25 C). For short hev trips in this weather the mpg is between 30 or 40 mpg.
Its a great car, I love it. But cold weather is no friend to electric or gas efficiency. It is nice to not have to worry about the car starting on cold winter mornings. Some of my co-workers' cars would barely turn over or wouldn't start due to dead batteries. I don't have that problem any more.
2018 Plug-In Ioniq
2002 Honda Civic