According to Military analysts technically VT-4 is much better than T-90 because of engine, auto transmission, stabiliser, computer, sensors, spot turn and many more that T-90 has not. Only thing is Vt-4 has not seen any action yet? Stats are all very good but we have to wait and see how VT-4 performs in real life fights.
Let me give you a simple example how to make any weapon system far more lethal than its adversaries of the same or modern generation. Dont buy a new one, improve the current one.
Deploy a VT4 in a exercise.
Let the tank commander run it around with other weapon systems based on the plans and execution of the EX. The VT4 crew completes its objectives at the end of the day. Now the processor with memory in the MBT has been learning (ML) all day:
1. Human crew and their decisions
2. Input from IBMS
3. Input from comms (including sensors)
4. Limitations of mechanical systems
5. Ammunition handling and firing through auto loader.
and other related factors.
This VT4's AI processor (machine language) with its memory has learnt (Deep learning). The MBT is now intelligent than it was yesterday.
Second day:
VT4 tank commander now allows suggestions (DL) from MBT for better maneuvering and lethality, which the MBT;s AI processor produces within seconds, with help from live data on 2nd day. This allows more survivability (as it assesses threats towards itself) of the VT4 and completing the Exercise in faster time than when it was only operated by human crew's decisions.
Third Day:
Now, the tank commander gives some leverage for autonomous operational capability of the MBT. The MBT has learnt in past two days, that's 48 hours, not 20-36 hours (excluding sleep) which is the limitation for tank crew coupled with fatigue which affects decision making. The VT4 does NOT wait for the tank commander inputs for all operations. The VT4 performs better than the first 2 days in the exercise.
Fourth Day:
The TC gives 100% autonomy to the MBT for all decisions. The MBT operates in the way that it kills faster, moves in calculations of displacement saving filters for longer life saving hours on engine maintenance shortening downtime while maximizing engine output in various terrains, cues and assesses targets beforehand through live comms/intel/datalink and assorts ammo for firing, and also helps other MBTs complete their missions in faster time by communicating with them.
In all this, crew remains fresh (no exhaustion, more time to process incoming data), only to take controls when the TC assigns control back to himself.
This makes the MBT more lethal, while it was never upgraded mechanically with add ons or bigger gun or more ammo or newer engine.