I voted to smooth out the top opening but make the lower grill opening smaller to retain cooling efficiency, especially South/Southwestern states models. See if you could also source out parts from recently totaled 2009-10 BMW's (maybe from smaller 1 or 3 series), especially for their grill air vent controls. Hack into it's new home (your project) & reprogrammed to your req's. The shutter mechanicals & servos are well-engineered, just hack to your specs & dims.
Should be a true ecomodder's favorite treasure hunt find.