Sadly, I think I am going to have to forgo making any claims of improvement for awhile. I was hoping to collect fuel logs that were a bit more conclusive, but they seem to be all over the place - using the same pump and station for all of the fills.
I just did a 49 mile test with the front discs installed and ended up with worse numbers. Perhaps they really do hurt the aero. Apparently it's going to take significant time to figure out.
I can't fathom any way the mirrors are not a win regardless.
Starting with a relatively clean car, I did bomb down a gravel road after logging my miles and shutting the generator down. That reveals some interesting dynamics I think.