I noticed the engine acceleration sound cuts off when making a turn in any of the tracked vehicles. It should still persist as the vehicles are still in motion, and not go all stealth mode. To be clear, the engine sound cuts off only when your either traveling forwards/backwards and you press A or D to turn. The engine sound fades out and you just coast silently with the track sound rustling, yet the tank is still going forwards. It's a shame cus holding A or D Makes a wonderful engine revving sound and could be used instead of the silence, or just use the normal acceleration sound, would probably work better.
This is the only thing that bugs me about tracked vehicles in Arma 3, other than that they sound freaking awesome.