volume/kWh also matters for car use-cases (but especially for less high end cars not as much as kg/kWh)

$/kWh is mainly affected by: material cost, manufacturing cost, cost of safely using it (e.g. shielding but also e.g. fire insurances), replacement cost (lifetime, frequency of repairs, needs full replacement for repairs?, refurbish-ability etc.)

As far as I can tell the material and safety cost should be much and somewhat cheaper, the manufacturing cost is hard to say but initially is likely more expensive as it's a new process and the durability and refurbish-ability are probably major points which will decide weather it's competitive in the vehicle market or not.