Well at least the important bit is covered, you can already get cars that adjust the seat and mirrors depending on the driver (by recognising different keys) - not that you need mirrors cos its self driving and you also won;'t need to adjust the seat. Music - ohh, if only there was an IT solution to that - maybe the music could be stored on some electronic thingambiginny? The choclate biscuits probably melt and go stale anyway, so we are down to sails & tools.
I think a more valid gripe about a 'shared' car is that there won't be one around at rush hour, when they are all busy, or after 10 pm when they are all busy recharging themselves,