As far as an actual possible marginal improvement to range when below freezing, without any modification to the car, the following MIGHT do something, and SEEMS like it did for me when I tried it, though it may just be me wanting it to do something. This is what I tried just for kicks.
If I were leaving at around 8:30 AM, set the pre-heat to come on at 6AM and set the end timer for 8:00 AM at 100%. SEEMS like I get an extra battery temp bar (5 instead of 4), and marginal improvement in rage, something like 3-5 miles, maybe, though I have not actually recorded data to determine this. So possibly will help a little, probably just crap I made up in my head when I tried it, and the net result was negligible. And it wastes a little power...