It's apparently not fuel but pressurized air being refueled by the car itself.
reply> "Will it even be maintainable?"
Probably doesn't matter. I don't think it will be permitted on public roads anyway.
The presented variant is invite-only, so I guess it will be made to put in the garage of some (Saudi) investor who commits a billion dollar investment...
Correcting myself (and Elon) here.
replyIt turns out the car has a 200L/600L nitrogen tank with 10,000PSI that needs to be filled from external source.
Consumed nitrogen reduces the pressure, so the tank is re-pressurized with ambient air by a in-car compressor.