What would you do with your aero gains: Spend them, or save them?

[MetroMPG]

Let's say hypothetically that you improved your car's aerodynamics enough to see a 15% FE improvement at 90 km/h (about 55 mph) compared to before the mods.

In other words, you could now drive somewhat faster, and still get better FE than you used to get prior to the mods. Or you could find the new, maximum speed at which you achieve the same FE you used to get at 90.

So, what would you do?

Take the fun poll!