Looking at the performance numbers for a BMW 328d, which was a long term car for Motor Trend, its 45-65 mph time is only 4.1 seconds. That's the same 45-65 mph time as a 2016 Mazda CX-5. For a car with 280 lb-ft of torque, I expected its acceleration to be faster honestly. This is what makes me think 175 hp on the CX-5 diesel might not be significantly fast enough for highway passing compared to the NA 2.5 engine.
These are all just assumptions from me though. I will know for sure once I can test drive one.