Sorry, but this is still wrong. I've been driving EVs for 5+ years now, and while the savings vs gas are substantial, its nowhere near 10x like you claim...unless you are comparing this to a v12 pickup truck, which is hardly fair. From my experience I would estimate the savings is about 3-5x less than gas (depends heavily on the price of gas at the time as well as time of year and how aggressively you drive). Supporting evidence to this from the Tesla website (click on how they calculate the gas savings over the life of the car...)
View attachment 318590
Also, when I was talking about the efficiency that is the efficiency of the charger in the car (yes, the thing you plug into the wall is not the charger.....). The charger inside the car is basically an AC/DC converter (batteries store and run DC), and that has a loss associated with it. Thats about 15% (I've measured this from the wall to the car many, many times...not on a Tesla but on a 2014 and 2017 Volt, as well as a 2017 Bolt). Also, depending on the battery temperature, the thermal management system may kick in to cool down/warm up the battery during charging, so 15% is pretty accurate. Has nothing to do with the power company and their transmission efficiency...
Finally, you made another common mistake referring to the battery in the model 3 as having '75 kW'....kW is a measure of work (1 kW = 1,000 Joules/s), kWh is what the battery capacity is measured in because the units of time cancel out and leave units of Joules...which is energy....ie, 1 kWh = 1,000 Joules/s * 3600 s = 3.6 megajoules. Since the units are large, its easier to call it kWh rather than MJ....
It has nothing to do with the SOC or how long it takes to charge, average price of electricity is $0.12 - 0.13 /kWh. If you take 10 kWh from the wall it costs $1.20 regardless of if you take 1 hour or 10 hours to do it, and because of the AC/DC conversion loss in the charger (in the car) you will actually end up with only ~ 8.7 kWh of useable charge in the battery while paying for 10 kWh of useage.