Due to long distance commute everyday, I'm heavily relay on usb charging on cars, Model 3 is a perfect commute car, but the front row charging is too slow for modern devices.
I tested the two usb ports below dashboard, with an 30% battery iPhone 7:
5.01v, 1.14a, total 5.71w.
and for an 50% iPad:
5.01v, 1.28a, total 6.40w.
So I followed @fseir 's video and did a quick work:
First I bought an anker 12v 5 ports hub, total output 5v/10a, 5v/2.4a each:
It's very easy to remove the cabin sides, and cables are fit perfectly within:
I cut a small pieces of plastic and insert the hub wire into front cabinet, applied the double side tape and attached it to the back of the mobile phone charging plates:

I tested the two usb ports below dashboard, with an 30% battery iPhone 7:
5.01v, 1.14a, total 5.71w.

and for an 50% iPad:
5.01v, 1.28a, total 6.40w.

So I followed @fseir 's video and did a quick work:
First I bought an anker 12v 5 ports hub, total output 5v/10a, 5v/2.4a each:


It's very easy to remove the cabin sides, and cables are fit perfectly within:



I cut a small pieces of plastic and insert the hub wire into front cabinet, applied the double side tape and attached it to the back of the mobile phone charging plates:


