Mark,
It doesn't have to actually add performance in order to end up being used as decoration on cars... The exaggerated wings, chin spoilers, and huge exhaust tips are more than enough evidence.
I'm with nirvana... If Boeing plays up those scallops at all in their ads (which they should), it's very possible that ricers will start taking hole punches to their huge rear spoiler wings in order to make them look scalloped just like the most modern airliner in the world. For a lot of those guys, it's all about looking cool/fast, not about actually being fast.