Well done !
Very interesting.
My dad had the same car as yours. I think it got 36 MPG highway - stock.
I wonder what kind of mileage results that you would get if you did a 'real world ' A-B-A-B test.
This would mean driving on a highway at 65 MPH or more without EOC, coasting in neutral, or any other tricks.
I told him how that you get 50 + MPG with the car, by EOC, coasting down hills , etc.
He wants to know what kind of mileage he would have got if he had stuck one of these on his car ( He is not a hypermiler at all - more the opposite... 'The Anti-miler'.)
I linked him the picture of your car, and he said " What is he trying to make his car look like a missile ? " To which my reply was " Well yes -he IS trying to turn his car into a missile ... instead of a BRICK ."