This is the Samsung Slide Liner, getting ready to debut at an Australian rugby match. It seats four and moves up and down the field to follow the action perfectly. It belongs in Formula One and here's why.
The problem with watching F1 in person is you just don't see very much of what happens on the track. Your field of view only covers a corner or two, so everything happens in the abstract. What you need is the ability to rocket around the circuit with the cars. it's the only way to have a full sense of what's going on.
We actually suggested something like this before, with a gigantic bus wheeling around the circuit, but seats-on-rails is probably safer.
The current top speed of the Slide Liner is just 20 kp/h, so there's some work that's needed to make this ideal for F1. Still, as WTF1 points out, how great would this be next to Eau Rouge?