A good surrogate for how many premiums are sold, when we had reliable data for a while in 2025, was spawns per day in the first few days after they went on sale.
It’s a reasonable presumption that if people purchase a product and pay it, they will tend to play it. If there is a significant difference between how many spawns two vehicles generated after going on sale, the one with more spawns presumably sold more at the outset.
I ran those figures around the time of the first Senrai sale comparing them to regular premiums:
Spoiler

The three Senrai premiums are on the right side in purple, compared to all other premiums offered earlier in 2025 color-coded for air/ground/naval.
A rough idea of the numbers involved, between the three Senrai packs there were an average of 50,000 spawns (AB/RB) per day in the first two weeks after they went on sale. This is about the same, taken together, as all spawns for the previous ground premium, the T58, which by itself managed 43,000 spawns per day in its first 8 days of sale (it was only $50 however).
The two previous Naval premiums (Nelson and Maryland) had an average of ~700 spawns per day in the first week after they went on sale each. This is mostly going to be a reflection of the much smaller naval player base, which only accounted for 1-2% of all spawns in 2025. The Gneisenau earlier in the year performed the best of all naval premiums by a considerable margin, at around 6,200 spawns/day immediately after launch.
Arguably the most successful premium in 2025 up to that point, the F-18, had 102,000 spawns per day in the first two weeks after IT was purchaseable, or about 145x what the later naval premiums did.
So the first $70 Senrai batch, despite an obviously much higher investment in marketing, did about half as well as the $80 F/A-18C (early), which was barely marketed at all. However, they did about 70x better than the $80 naval premiums. Naval premiums, it’s clear, make nowhere near the gross revenue for Gaijin as a good air premium will. How much they cost to make is unclear but to be economical they’d have had to cost less than 1% each of what it cost to make and market that F/A-18C, which seems unlikely. The Senrai offering seems to have done fairly well compared to other ground premiums last year, but three air premiums and one ground premium (T58) sold significantly better than the individual Senrai tanks.