This must have been suggested before, possibly by me even but instead of seeing 1L or 0L, it would help if we could see 0.3L or 1.9L etc. As it is you purely have to guess and hope that you've done your calculations exactly right. One thing i think i've noticed as well is that when your fuel goes from (for example) 2L to 1L, it isn't going from 2L to 1.9L, it's going more from 2L to 1.6 or 1.7L. I noticed this on one race where i was coming into the pits with 2L, just before i reached my pit box it changed to 1L, then after the race i checked and it said i pitted with 1.6L.
So yeah, seeing a decimal point there would be uber helpful for strategy. F1's about precision, no? :P