S4's can break oem diff carriers when you launch the shit out of them, I am very aware of this. I'm not talking about that, I'm talking about when just driving aggressively on the street. But the difference is that an M3, RS5, S4 aren't drag racing cars, where the mustang is built so that Bobby Joe can leave high school football practice, take his date to makeout point, and beat 600hp 12sec Supra's the next day at the strip.
I do like the new Mustangs, Ford is really getting their shit together but it's not a German sport sedan.