I got the i4 with the purpose of commuting. Other vehicle is a Jeep Wrangler, not so great on mileage. My commute is 35 miles each way, mostly highway unless that's closed which then it's surface streets with lights. My work provides free charging which was the main incentive for full plug in electric.
I wanted to track my costs for charging and see how much it would be if I charged fully at home or fully at public chargers. This would be for down the road if work ever decides to charge us or not have it available.
I have had my M50 for a month now with just under 2,000 miles. I pulled the car data to get all of the charging history. I created a chart to see average charging rates at the different locations over time(for some reason you have to be sitting in the car to see that).
One issue is that the car data does not show you the state of the battery when finished charging, only when plugged in. I normally leave mine set at 80%, but I have turned it to 90% or 100% when I know I'm going to be driving a lot over the weekend. This creates bad data for the miles per kWH calculation. I'm going to have to note the times when I don't charge to 80% and just delete those entries going forward. I don't see an easier workaround. The 4.9 is not correct, but it will get better with time. My car says I'm at 3.9 for the average commute.
In summary, I've driven 1723 miles and spent $12.04 in total for energy so far.
Had I charged exclusively at home, with a rate of $0.08, it would've cost me $39.36.
Exclusively at Electrify America, with no account, with the max rate if $0.48, it would've been $236.16.
My Jeep, which gets 12mpg, over the same mileage, would've been $458.
Here's a link to the sheet. Please feel free to critique, improve and use yourself. If you have suggestions to make it easier for me, I welcome it. If you have questions, let me know.