At operating temperatures, a modern ICE w/ a 3-way catalytic converter driving at highway speeds through the right environment (L.A. on a bad smog day) could easily have NOx and VOC levels at the tailpipe that are lower than what's going into the intake manifold.

this is literally how Ford marketed their PZEV (practically zero emissions vehicle) cars around 2003. https://www.latimes.com/archives/la-xpm-2004-jun-09-hy-neil9...

That's true, and has been for quite some time. Still: NOx and VOC, but not CO2.