What are some actual prices people are paying??
(often local regulations are a major factor.)
Charging at home at night often the lowest cost electricity.
I believe 10c/kWh is what I'm billed after my solar panels were removed for roof replacement.
Don't know yet if the night time charging would be lower, trying it this month.
To be fair, for M3 size of the car, the efficiency of an ICE car should be between 30-40mpg. My stick shift 2001 Corolla used to be ~40mpg.
So, assuming 35mpg average for class and with M3 getting close to 4 miles per kWh, you need to pay (gas price per gallon)*4/35 for equality.
Looks like with the current declines in gas prices we have $1.80/gallon. So, 21c/kWh is an equal rate.
However, to be more precise we need to adjust for road maintenance tax, which I paid separately during EV registration - $50/year and which roughly equals to what was paid for my prior ICE usage during the course of a year out of gas road tax.
Federal road tax is a fixed 18.4c/gallon.
Therefore, subtracting this we get $1.616*4/35=18.5c/kWh of an equal charging rate.
I.e. I'm saving 1-(10/18.5)=46% on electricity (actually more, since my former car was ~30mpg).
The gas prices are quite low though currently and if you are moving from a larger vehicle to a M3, your savings would be higher.