[Invertigrate]

Have you considered purchasing a newer car that you can modify?

I would assume that it would be trivial to just remove the antenna for the mobile data and once that's gone then 1, 2 and 3.

As for the touchscreens you always have buttons on the steering wheel so you will have to be content with that.

[MrDrMcCoy]

I'm concerned that really new cars are always expecting to be able to connect eventually, and that as a result it would start having issues after being disconnected for a long time.

[Invertigrate]

I don't think they implement that into the cars as developers have to consider that a car may be unused for a longer time and perhaps even be completely discharged.

I think this would be the best approach for you as you would get all the advantages of having a new car while still remaining "off-the-grid" as long as you don't bring your phone with you.

[yellow_lead]

If you look in the car's manual, you may find a fuse for these you can pull as well. May be easier than disconnecting the antenna.