I'm really interested in the best way to do this. I have 2 Spark EVs - a 2014 with only 5000 miles on it that I've had for 2 years, and an 2016 with 23000 miles on it I got last month. I know there's a difference between the 2014 and 2016 model, but on these colder fall days, the 2014 is topping...