BrockWI wrote:Totally out there, but I have put a portable 5 gallon plastic water tote in the back seat between the kids filled with 120F water. The kids really liked it and it was amazing how much heat it added to the car when it sat outside (at 0F) for an hour and then we got back in again.
Interesting idea. Let's say that you want your car cabin at 60F during cold weather, then if your water starts at 120F the water changes temperature by 60F. Water weighs 8.34 pounds/gallon, so 5 gallons is 41.7 pounds. Then by definition the heat given up is 41.7 * 60 = 2500 BTUs.
2500 BTUs equals 0.73 kWh, so you've saved about 3 miles worth of battery charge. Maybe more like 5 miles, given the overhead of heating the coolant loop and the heat losses that occurs in the coolant loop outside the cabin. Of course, the extra 42 pound of weight has a range penalty.