Finding Nemo

,

Here is a blank chassis for example purposes, marked in red are a composite of what teams in Time Attack had been typically removing around 2012. Most teams were leaving the frame rails intact, only removing the sheet metal between them. 

This also meant that they would use aftermarket tubular sub frames bolted to the stock locations.
 
In the next image you can see what Nemo had removed, the entire rear seat shelf and the frame rails on either side, everything else, all the way back.  The rear subframe was connected directly to the tubular roll cage structure, stiffening the rear suspension and creating space for the massive aerodynamic tunnels that passed air through the rear suspension.

It’s easy to see what people were concerned about, with the cars creeping ever closer to purpose built race cars and losing their roots as tuner cars. The part that few people realise is that Nemo was not the first car to do this, in fact just a year before Nemo debuted a car that had gone nearly full tube chassis, competed in anger, and took a podium.

That car was the Revolution RX7.

They had removed the entire floor pan, replacing it with a sheet of carbon.  In this photo you can see the rear section of this beautifully constructed car.