Mine seems to do the same thing you describe below. And I have not found any discernible difference between Drive and Sport. I had my dealer look at it, and they said it is performing within specs. At any rate, keeping a keen eye on my inst fuel meter, I am getting about 27 mpg on premium, so I am happy. And when I am in a spirited driving manner, I like the way this auto shifts. This is my first auto tranny car, and this is probably the first auto I have driven that I am pleased with.