Or maybe adjusting toward reality? See Real World MPG Thread… depending on the rig some there boast mileage that matches up to sticker. Many are 16-19MPG (I got this on my previous non-Pro 2006 T4R. But my Pro sucks.... 14-16MPG with 18-19mpg as best case scenario in ideal freeway conditions. And this is without serious mods... just tube steps and Yakima Aero bars really are all that would hurt factory mileage really. Personally I think even 17/21 on a TRD Pro is a pipe dream.
JC
My guess as well. Adjusting towards reality, but if anyone calls them on it they can blame it on TSS or other things that shouldn't actually affect mpg that much.
As a side note, dealers in Northern California said they'll start getting non-TRD Pro trims early October and TRD Pro some time after that based on what they're seeing for their allocations.