Brake drag reduction clips
 

These come as original equipment on some cars, but not many. Turns out you can get an aftermarket version. They pull the brake pads slightly away from the rotor when not braking.
VIDEO: Installation of NAPA Drag Reduction Clips for Better Fuel Mileage | Safe Braking

A friend of mine was thinking of putting them on his wife's honda. He found some for sale at rockauto.com but that was a few years back. Even he said he wasn't sure if he would see a return on his investment though I think they were only $8 or so.

It is a good idea though I guess most people don't care enough for it to matter.

I wonder what something like this would do for my FEH since it has 4 wheel disc brakes, and the vehicle relies primarily on regenerative braking.

Found several Raybestos ones on Amazon in the $6 to $12. Thing is there was no way to determine which clip would fit your car. Raybestos own site didn't even have the clips listed.

Came across a blurb in an article stating GM started incorporating a spring in the abutment clip for this purpose. Have to remember to check the Sonic for it when a rotate the wheels.