Plug-in hybrids makes very little sense, compared to pure hybrids or battery-electric vehicles. You end up with a complex drive train and a lot of added weight.

Plug-in hybrids makes very little sense, compared to pure hybrids or battery-electric vehicles. You end up with a complex drive train and a lot of added weight. To me it makes more sense to just use a hybrid if range is an issue. You need quite a large battery to drive 100 miles, and in your example you end up with an engine that is only used 10% of the time, but costs quite a significant portion of the overall cost of the car. You also have the added maintenance costs, which are higher for plug-in hybrids due to much more complex drive train. The reality is that for most people this is a non-issue. The biggest issues in temperatures that low is that your combustion engine won't start because your 12V battery has failed. All solvable, by just using a block heater. Which incidentally is the same way you can mitigate a lot of the range losses due to cold battery in EVs.