Its tons/hr not tanks/hr.
I would like to understand the logic that drove you to this conclusion though, as it makes zero sense as stated. If you are using 1.74 "tanks per hour" then your 2t sidewinder tank would be empty in 1.15 hours. Certainly not the case.
What is this "tank" unit you are referencing?
I think he's confusing the segmented indicator for the Main Fuel Tank. On small Ships it's segmented, whereas on large Ships with large Fuel Tanks it's non-segmented.
I think the Segmented indication stops with a 16ton Fuel Tank equipped.
These indicated Segments are purely a visual thing though and don't have to relate to anything (i.e. 1 Segment = 1 ton) although on some Ships and Configs that correlation can be the case if I'm not mistaken.
There's indeed just a "Main Fuel Tank" and what I'd describe as a "Feed Tank". The Main Fuel Tank will always fill up the Feed Tank entirely, once it is empty.
Should the Main Fuel Tank i.e. only hold a tiny fraction of that - that'll be all you get during the final and last Transfer.
Whatever is then remaining in the (not fully filled) Feed Tank is all you got - and no later than this Moment running Fuel consumption will become the biggest concern.
tbh though, I've never dived deep into the Fuel Systems of different Ships, so I don't know the exact size of that Feed Tank on a Sidewinder, Eagle, AspX or Anaconda (?)
(50000LY from Home right now, so I can't experiment with that Detail on different Ships)
I guess the lack of easy overview for "Fuel Endurance" (translated not directly into range but in-System "Flight Time" instead) is credited to the fact that it's typically not a factor at all.
HyperJumps instead are the defining factor to Fuel System Management, hence the Galaxy Map gives the required visual indication, plus the HUD Warnings about last scoopable Star enroute etc.
Audio Warning "Main Fuel Tank drained" is more like a final Warning, highly encouraging to (no later than this moment) take care of Fuel Management ASAP and make it the top priority.
A trip to Hutton in a small Ship is likely the sole, distinct exception where this can easily become a significant factor.... but who does that ? xD
(and with no reliable fixed ETA, only experience yields the projected ETA and consequently the Travel time. 85mins at full Throttle if memory serves me right, ~25% more when using SCA... that then needs to be multiplied with the running Fuel Consumption of Tons/hour to make the needed calculation - and maybe consider having enough left to divert and still make it to an Alternate (HiWake after an Interdiction) )