I’ll tell you one thing, I will never complain about Z printers wasting too much ink ( not that you are in this case you are just curious ).
These printers were designed by great engineers to save ink and not waste it in unnecessary cleanings and insane black ink purges. This is the exact opposite of Epson who has designed their units to consume as much as possible. That’s no accident.
The Hp ink carts face down and drain every drop and their cleaning mechanism uses as little ink as possible to keep nozzles clean. How do I know this ? The waste tank. I can go for many many years without replacing the spittoon. So long that I always forget how long it was. I mean you can go practically the life of the printer without replacing one.
On my Epson printers they need to be replaced or reset about about once a month if used a lot. You look in there and that’s a lot of ink. My Canon tank lasted about three times as long as the Epsons, ( their carts face down too ) but no where near the economy of my Zs. The other thing I’ve noticed for many years about my Epsons is that once the ink levels go down about halfway, you start seeing more missing nozzles, or at least I do, and these require, you’ve got it, more ink. This must be because they are loosing pressure. I’ve found when my carts are full I have practically no missing nozzles with this new head.
We complain a lot about HPs poor software support and other issues with the new ones, but I’ll never forget how good they have been in economy of use, both in head design and ink use. That’s good honest design.
John
It seems that the ink-levels are fairly vague estimates. From the web-server help:
"The data provided regarding the total ink consumption are approximate. HP does not warrant the accuracy of such data; the average error in the total ink consumption can be up to +/-15% in about 95% of cases. The error percentage can be higher in the remaining 5% of cases. This is based on HP internal tests run in ambient conditions."