[Fat Charlie]

Coast down, indeed. I'm still trying to come to grips with how to maximize the benefits of my first ever aeromod. My numbers are improving as I learn how to drive my now different car differently to take advantage of it, so the mpg numbers tell a story that's more about me than the mod.

Yes, the trip numbers are the practical result, but they tell about how the mod helps one driver on one route. My search fu is weak this morning, but there was a thread some time ago about removing wiper arms from an Insight (I think) and getting somewhere like a 15% jump in FE. The OP was suspicious and determined that at his normal speeds the slightly reduced aero load let the car stay in lean burn where it otherwise wouldn't have been. I think the Civic may have the opposite problem, a drag reduction that for some reason isn't translating directly in to higher mpg.