I mean we mostly are, it’s most of our tools, liter’s etc on all our packaging. Speedometers have it. Some states like Maine have it on the highway signs. The military operates in kilometers and meters. I don’t know what the hang up is honestly.... fortunately the U.S. space and aerospace domains were metric a long time ago.
I find liter’s per 100km a lot easier to range estimate than mpg. Metric in general is just easier.