[aerohead]

I went to the Munich, Germany site.
I reverse-engineered an estimated frontal area.
I reverse-engineered the VERSUS ENGINEERING test velocity.
Using Munich's drag coefficients for the wind tunnel tested-model, I reverse-engineered for VERSUS's velocity.
With their own numbers, I calculated that the 'smooth-bellied' notchback with diffuser would have 39.1 fewer counts than the 'dirty-bellied' notchback with diffuser, making 13.82% lower drag.
With only the smooth belly and diffuser, the IONIQ might hit it's target of Cd 0.20.