There are some cars that can only access 3G for certain features and it would be cool to test around and see what my vehicle can do and if I want to disable it for reliability reasons

So, thanks for this edit, because I now have the plan -- Dad gets to geek out and they get simple texting / calling but none of the other related phone bullshit. I'm pumped!

Indeed, but good luck setting something like that up and not upset a legitimate cell tower or other user of a frequency band that can be spoken by LTE equipment.