They cost extra fuel because they are superior units. This also goes for the kv1 which basically is more durable t-34
Thank you for confirming yet again that last time you've seen soviets up close was during intro.
KV-1 at its current stats can deal only with P4 and even that is fully RNG based. Or in other words, P4 have MORE chance to win against KV-1 frontally, then T34/76 have to win against P4.
KV-1 is a slow, not at all durable(nerfed HP by a HUGE amount, KV-1 have less hp them T34/85, increased AT on everything) tank with a gun that belongs to flanking vehicle, yet its unable to flank anything.
In its current state, KV-1 is reliable only against an Ostwind and nothing more, while T34/76 is a game against all tanks due to its speed, so think again before calling it superior.
Now, when it comes to all other call-ins that actually ARE effective, instead of increasing their CP, which will change nothing, increase their fuel price so they can't be spammed as easily and loosing one can actually be felt instead pumping one tiger after another.