Chain Bear F1 on YouTube has great video from an incident last season which helps explain the floor setup.

https://www.youtube.com/watch?v=rUC2gDPiHEc

>What about the underside of the vehicle?

A very astute question. Yes, as much effort goes into the design of the underside as does the shiny side.

The most recent article I found via a quick G search is from 2013. For sure the rules have changed since then, but it's still a fair benchmark to illustrate the complexity of overall design with regards to the aero.

"https://www.roadandtrack.com/motorsports/news/a18417/the-sec...

It used to generate a big fraction of the downforce, so much that drivers pressed the accelerator when going into corners.

http://formula1-dictionary.net/ground_effect.html

Right now this ground effect has been banned and it is mostly flat, except for some things in the tail.

Floors in F1 have been flat for a while with the exception of the FIA mandated plank down the middle.

The rear diffuser is sometimes blocked from cameras when the car is parked. For example 2009 with the double diffuser.

There isn't that much teams can do on the underside of the car. A lot of effort goes into preventing air from "leaking" under the car in the first place.

While you don't see the underside of the car much (for obvious reasons), the occasional roll-over crash (or crane lift after a 'regular' crash) gives us a glimpse from time to time. Check out Nico Hulkenberg's crash at Abu Dhabi pay year for a good example.