The Abrams’ gas-turbine engine sound is pretty much perfect now, but the diesel engine sound of the Leopard 2 family is still noticeably inaccurate.
I would reccomend you make a bug report for it, if possible.
Also maybe try a soundmod for the time being, until Gaijin meddled with the sounds again.
Feels like too much hassle. I’ll just live with it and keep playing.