Drivemode power curve mpg gen 3 vs gen 4

I've read on some posts here that the gen 4 power curves are different from the gen 3's in the same drive modes. One post says the gen 3's PWR is now the gen 4's normal, which is why the gen 4 feels more peppy. Is the fuel economy rating based on accelerating at a specific rate, or do they test in a given drive mode and throttle position? Say if I were to accelerate 0-45mph in 7 seconds between stop lights on my way to work everyday to keep up with traffic, would I stray further away from the rated EPA mpg running a gen 3 or gen 4? I understand the EPA has adjusted the reported mpg/testing methods over the years and am hoping to ignore them for comparison purposes.