azrealswrd: Ben suggested I use lime green tape for my temporary mods. Nuh uh.
I bet your blue tape got lots of attention.
The fact that you thought it was quieter tells me that's probably a worthwhile aeromod.
ChristphrR: well, I did the other light this evening, and measured it. Total gap area (projected) around both headlight assemblies is
43.2 cm2, or 6.7 square inches - practically the size of a business card.
I figure: if I've got a business card sized hole smack in the front of my car that does nothing functional, and ultimately lets air into the aerodynamic torture chamber that is the engine compartment/underbody area, why wouldn't I cover it up?
GM obviously thought it was worth putting speed tape over the headlights (and other panel gaps) to squeeze max efficiency from the GM EV1 / Impact for its record setting speed run:
Will post pics of my weatherstripping mod in a few minutes...