Jalopnik posted a video interview with the chief engineer of the new Silverado today.
https://jalopnik.com/all-the-cool-st...evr-1822399931
Most of it is generic, but at 1:20 there's an interesting detail regarding the air curtains. Mr. Herrick mentions that they're good for an 11 count improvement in drag (-.011 Cd). I think this is the first time I've heard a quantitative assessment of the impact of air curtains from an OEM.