Credits per Minute (Net) = Credits per Minute (Gross) Error
i just noticed that there's a bug in the Credits per Minute (Net) calculation.
It seems as the costs are not subtracted anymore since some recent patch.
I just bought the T34 new and for this tank, Credits per Minute (Net) = Credits per Minute (Gross).
You can also check e.g. this page
All Tier 5 non-premiums. Due to the bug, the new Japanese Tank gets an absurd high value O-I Experimental : 4,597.15 cr
The gross value
O-I Experimental 5,674 5,354.20 cr
Means operating costs of 800 credits per minute (!). 2000 are normal... (?)