WarThunder’s tank engines are extremely simplistic. All engines act as having the exact same power curve, and it likely doesn’t fit any singular engine perfectly.
Really, the only thing that WarThunder can get right about tank engines is their minimum RPM, their maximum RPM and the horsepower they produce at said maximum RPM. Everything else (engine accurate torque and horsepower curves, which honestly are probably the most important aspects of engines) are simply not modelled.
There’s no clutch. There’s a “manual transmission mode” where you can just switch gears up or down, but you don’t need to clutch or anything else. You use the cruise control keys (Q and E by default) to manually go up or down in gears. You also don’t even need to turn on manual transmission mode on to have that functionality with the cruise control keys. They do that even with the automatic gear selection.
But speaking of transmissions, much like tank engines they are also very simplistic. They are just collections of gear ratios (and therefore top speeds), but there is no regenerative steering or steering radii/ratios, even neutral steering is just it’s own gear ratio that determines the top speed of the tracks when turning in neutral.
Ever noticed how most post war tanks (and even some WW2 ones) just have far more gears than they should? A lot of it is because right now WarThunder cannot model torque converters, and so their aspect of multiplying torque is “modelled” by just adding extra gears to tanks.
And of course then there’s electrical transmissions which are their own problem which, yet again, WarThunder cannot model.
There’s also another problem which is that all transmissions, much like all engines, are treated to be identical in function.
Edit: Oh yeah I also forgot there’s even more issues with tank engines in that only gross horsepower is considered, which is the total horsepower created by the engine, when net is the actual usable output after some has been used by cooling, friction and such.