Is it just me or does it only sometimes work, especially in remote view? Switching surfaces can make the UI disappear (and not reappear) too, it seems. I frequently spend long times in a tank on Vulcanus, not getting out for days so...
I never tested the mod when remotely driving, but I'd guess that it tracks the fuel of the vehicle that your character is in, rather than the vehicle that you are currently driving. I'll try to take a look at this.