It is because the pump and the car can communicate with each other, work together to select your preferred fuel, and fill the tank without the driver being involved. Like gliding through E-ZPass, you would be paying with a cloud-connected app that, by then, may be standard on most autos. If your vehicle is self-driving, you should be able to be happily ensconced in your bed or at your computer while your car buys the gas without you even being there.
The gas station of the future
A lot more than just a place to refuel your car
Source: Oliver Wyman
This article first appeared in Forbes.

