Since we don't require a front license plate in our state I decided to remove the front license plate from our Spark EV and our Gen 2 Volt.
The Spark was just screwed into the plastic bumper cover and was very easy to remove. The Volt required drilling out some aluminum rivets but was not much work.
I've read a lot about filling the holes and didn't like the look or price of the bumper plugs and didn't think they would work on the Volt either due to the hole locations.
I ended up using paintable caulking (~$5 Dynaflex 230) and AC/Delco touch-up paint ( ~$17 ACDelco 19328529 Switchblade Silver Metallic (WA636R)) When searching for touchup paint the reference number for your paint code can be found on the silver sticker inside the glove box.
After removing the plate holders I made sure the edges were flush and smooth with a sharp knife.
I applied the caulking and since it was water based cleanup it was very easy to smooth and remove any excess.
The caulking shrunk a small amount after curing and left a small indention in the middle but it is still less noticeable than the bumper plugs IMHO.
I then applied the touch-up paint and clear coat to match my car and it is a very good match for our Volts silver grille as well.
I've included some photos below of the finished photos of both cars for reference in case anyone else wanted to go this route.
Since these holes are located so low on the car we don't really notice the slight imperfections where the holes were.
We already had the caulking and a caulk gun so we only had to spend about $17 to fill all 8 holes, this was the best and cheapest option I could find for the money.
Close up low level photo after paint and clear coat:
View standing near the front of the car:
Volt close up low level photo after paint and clear coat: