I'd like to track my overall usage/cost of driving and was wondering if anyone has found a good way to slice the #'s. For example, my first 221 miles showed 44kWh used. At $.04/kWh = $1.76 But then I drove 179 miles, with the car showing 52.7 kWh used. I stopped at a supercharger and got 132 miles back so I'd like to show that at $0.00 but I'm not sure what to do with the other 47 miles from the day, or how many kWh that represents. It was all highway driving, so should I just average it out and say 1 kWh every 3.4 miles, so 132/3.4 = 38.8 kWh "free" and then 13.9 kWh "paid" once I got back home and charged up? Thoughts?