I have free lifetime supercharging (2014 P85D) and i have pondered this question because if I ever get into an accident and the car is deemed totaled i will need to find a way to put a dollar value on something like this. I just made this spreadsheet, i cant seem to attach a excel doc to this post. But i made a pic of all the formulas along with the data so if you want to make your own sheet you can.

The best thing I've come up with is pulling the data from the car about how much you've used SC in the life of the car, I'm currently at 21,647kWH of DC charging over 120k miles in almost 4 years. I expect to keep the car forever but that is an unmeasurable number so lets say i plan to have it another 10 years and do the math on that to calculate an average and put a value to it.

So that's 82 miles per day i drive on average

That's 300,000 miles in 10 years, which seems low IMO but lets keep going with the maths

Which is 180WH per mile if only SC was used but it’s a mix of DC and AC charging so we have to add the 22,723kWH of AC charging to the total now at 44,370kWH

So its 369Wh per mile which is about my average so i know the maths were done right so far.

That comes out to 110,925kWH over the next 10 years.

but now we have to account for AC charging, which right now is about 51% of all my charging. But that number has shifted over the last 3 years it used to be 85% was AC but in my current house my only option is to charge via 120V outlet so i tend to do A LOT more SC than i did before.

So for the sake of argument I'll say my SC rate is 70% of the total kWH for supercharging over the next 10 years is about 77,647kWH

**now that needs to be converted into a tangible dollar value**
I don't know the exact price for supercharging because it’s free and thus doesn’t display the prices on my screen like it does for others. I will use CA as my example as that’s where i currently live. I have heard prices range from .20 to .43 so i will split the difference and call it .33 for my equation, if it’s wrong then someone please let me know so i can edit and change the formula.

Using all the values above it comes out to $25,623 over the next 10 years supercharging would cost me if i were to get a new tesla that doesn't include free SC anymore.

Now $25k is pretty extreme and no insurance company will ever pay that out. But if you can prove the maths you can at least make a strong valid argument for increasing the value a good bit.

In my case free SC came with the car when i bought it as a CPO from Tesla as it was part of their early adoption incentive and was one of the reasons i got the car in the first place besides the raw power it puts to the ground. So since there was no additional fee for free SC when i bought the car, it was included as part of it then i have the argument that the $25k is part of the value of the car when i bought it.

What i dont know how to calculate is the free premium connectivity. I have an enterprise loaner right now and it doesn't have premium connectivity and it sucks ass but i cant place a dollar value on something being a PITA yet.