Originally Posted by Arco-Zakus
The answer is that our government (EPA) does not trust us to do it "right" and get high enough average mpg. I think for every lead foot winding it up to redline there would be another gas miser doing the geezer style to max fuel economy, and it would balance out overall.
The EPA would treat it the same as a manual transmission. When a car maker performs mileage testing with a manual transmission to present to the EPA they have a professional driver trained to shift for the best possible mileage. The EPA knows that not everyone will shift for the best possible mileage but they accept the best-case results. They would certainly do the same for a "trainable" automatic.