Ok awesome, because I read elsewhere that if the car was ever for sale at a dealership then Tesla would recognize that and strip it of free supercharging. I read that the only real way of guaranteeing it will be preserved is through a private sale directly from the previous owner to the new owner, I guess this is not the case then?
The car has to stay away from Tesla, as long as Tesla never got their hands on it then you're good. That's the tricky part because dealerships can buy Tesla cars from auctions that have come from Tesla and therefore the FUSC is stripped.
For example, if someone trades in their 2014 S85D with FUSC to Tesla for a 2022 Plaid then Tesla will strip the FUSC from the 2014 model and if that 2014 model makes it way back out into the open market, it will no longer have FUSC.
Also keep in mind that not all older cars with FUSC will transfer. It has to be the ones with the SCO1 code.