[aerostealth]

I have been puzzling on how to accurately post gasoline logs for our 2015 Ford C Max Energi and account for the electrical consumption at the same time. My method involves treating electrical energy used by vehicle as fuel but treating the electricity that comes out of the wall (involved charging losses) as cost.

For example if my vehicle travels 400 miles at 75 mpge but uses 60 kWh of electricity to assist in those miles I convert electricity to gallons of gasoline equivalent by kWh/32.777. In this instance 60/32.777 = 1.83 gals e. In this instance also the car would use 400/75 = 5.333 gallons of gas + 1.83 gals e = 7.163 gals e. 400 miles / 7.163 = 55.84 mpg e.

However at 82% charging efficiency 60/.82 = 73.17 kWh to charge. This fact needs to be factored into the cost (not the vehicle watt hours per mile) so what you would do is calculate the electrical cost to charge. 73.17 x .08 = $5.85. If your gasoline cost $2.00 a gallon then your 400 m/75 mpge = 5.33 gallons + 1.83 gallons e = 7.163 gals e of gasoline for the entire trip miles.

If 5.333 gallons of gas cost $10.67 and 1.83 gallons e cost $5.85 then your total cost is $16.52. If that then 7.163 gallons of gas e would cost $2.30 averaged cost per gallon if you $16.52/7.163 = $2.30.

This method while a bit involved disentangles gallons equivalent and the actual cost equivalent per gallon. The electrical efficiency of the vehicle combined with gasoline is a separate matter which in calculated in the MPGe figure using this method.

If you look at my C Max Energi local driving log you will see this method being used. This is why you will see some non traditional gasoline cost figures but it is accurate for the cost of energy in versus the energy in the the vehicle battery/gasoline efficiency per mile when done this way.

P.S. My cost per kWh is 8 cents. This is my electric utility buyback rate for my Grid Tie Solar. It shows up as less money back from the electric company.
32.777 x $0.08 = $2.62 gal e averaged. However when blended with cheap gasoline the average is lower. If gasoline prices were higher then this it would lower my average cost. Since I am in effect blending 40 MPG with 95 MPG e performance it is a win win situation. The larger the percentage of electrical miles the higher my MPG e gets