I guess this is an old issue, but I'm sure there's a big user base of Americans that would love to be able to ask CC about fuel and know the gallons remaining, instead of liters. As it is, you have to guesstimate on the fly.
Personally, I don't like overlays to flip thru taking my attention off the track, so using voice with CC is really cool. If I knew my fuel exactly on it'd help me by knowing when to conserve, as I want to carry the minimum possible. doing rough conversion estimates hasn't worked, as either I run out by overestimating or carried to much/pit to soon.
I'm really no good at math and using voice with CC has helped me concentrate more on the races so I don't have to clutter my screen or flip thru the black box.

thanks for any info or tips!