Diesels has been famously tested "poorly" by the EPA, then tend to do much better in real-world driving. Ask a former VW diesel owner.
Anyway, I wouldn't hold your breath waiting for the diesel to hit the US market anytime soon, since Mazda hasn't officially released hp and torque specs, and we all remember that they promised a diesel 6 with the 3rd-gen debut 5 years ago...
Mazda spent a long-time trying to figure out a way to make their diesel engine perform well without needing to add that after-blue treatment shit that other diesels use. Looks like they finally figured it out and were ready to release the oil burner to the NA market, but the VW scandal came around and they delayed things again. Plus Diesel was always frowned upon in the NA market even before the VW scandal, so I guess they were hesitant to bring it here. I would expect the power figures to be the same as everywhere else - 175HP and 310ft/lb of torque.