Define "automatically" - where? how? I don't quite see the use case. In a city (where gas stations are abundant): indicator lights up, hey look, I'll be passing (any) gas station within five minutes. Outside a city, let's say I'm an hour's drive from a gas station - now what, a gas truck drives up to me? That might be somewhat expensive... Now, if this included periodical check-ups (lights, various fluids, pressure e…
There are uses cases, see: My wife works in an office building and the parking lot is paid monthly. She HATES going to gas stations and once a week I do that for her. I would easily pay +10 bucks on that parking 'subscription' to have them fill the tank for me. They already do this kind of service for car washing.
This could be a workplace option. Find a large business, present this as a benefit, sign up all the people too busy to stop by gas stations.