In these days of high gas prices. I was curious to see what the real energy cost savings are right to now. Back in 2017, we had the option to get a $5K rebate or unlimited free supercharging. This was because they dropped the price of the car by $5K before we took delivery and Elon was being charitable. It made no sense at the time not to take the rebate but four years in I was curious. What's the payback based on real usage?
First some figures while I could calculate all the fuel costs of our Tesla Model 3. Given the new details in the charge stats page of the app, it was easier just to do a point estimate from the last 31 days.
So the net of it is that we used 430kWh last month of which 40% was with Superchargers. That way pretty average month with three trips. I would guess a big percentage of our miles have been road trips. Since we were remote workers even before the pandemic.
Math-wise, it is about $0.15 in Oregon and Seattle is $0.13 for marginal rates above a base. To do some math about 33.4kWh is equal to the energy in a gallon of gas. So that's the equivalent of $4.32/gallon.
But, electric cars are way more efficient so our typical usage is 260-280W/mi. So the car is getting 119-128 miles per gallon equivalent!
So back to the original question. We avoided 40% of the 430kWh and on average Tesla charges $0.28/kWh or $48 last month. Extrapolating that is about $580/year. So it will take a long time to get through a $5K credit; over eight years!
Of course, most of our miles are much more than 40%. So this year are taking three 800 miles trips. So they use 2.8GWh and in a strange coincidence that we pay .28/kWh while driving at 280Wh/mile or $0.07/ mile. So that adds say a paltry $268/year so it’s 6.5 years to break even!
A final aside is I just remembered we subscribe to Teslafi.com so I have exact figures. I was wrong our lifetime usage is 41% so the last 31 days were exactly average. So over four years, 6.2GWh were free but the pacific northwest charges it turns out to be near impossible to figure this out but someone did click on his in-car system to get an estinate and its $.35/kWh in Washington and $0.33 in Oregon so so far weve got back about $2k of $500/year. Put another way, it is a ten-year postback!
EVs from an operating cost perspective are crazy good if you can afford the initial cost and that's why it's do hard to spend $5K 🙂