In this video I am demonstrating regenerative braking with a 100% charged battery in our new Tesla Model S 60 (applies to a Tesla Model X 60D as well), which is one of the advantages of having a 75 kWh battery software-limited to 60 kWh.
This clearly confirms that regular charging and regenerative braking is not using the same logic. It's charging limited by software vs. BMS using real SoC.
If starting like this on a really high hill, will it charge till ~120% (~ 72 kWh)? What do you think?