I have a heater on my Dragon. jemorga put it on and has one on his Proton as well.

There are different types. The one I have attaches to the bottom of the oil pan with adhesive (no problems so far). The plug is run along the pan and then to the front cladding. A small hole in the cladding open area (where rowhards openings in the skid plate are) and a zip tie hold the plug in place and make it easy to find when pluggin' in for the night. It is not noticeble during the day. Doesn't require a lot of juice and it just keeps the oil warm, not operating temperature. I notice that the heater warms up about 10 minutes faster using it.

jemorga put one on his wife's Prius Hybrid but it does not help any since the car starts our the day with the electric side...

If you would like some pics let me know and I'll get some this weekend.