it's a 1.5 liter with no torgue... it can't lope along at 1800 RPM like a 3 liter
ANY debate about the AT's gearing being more appropriate for the engine seems silly, since the AT drivers are constantly complaining about their MPG and the MT drivers seem to be pleased with their fuel economy

 

An automatic using the cruise control on the highway can downshift if needed to go up a hill and still remain engaged. With the manual, once the clutch is press, the cruise is disengaged. The higher revs of 5th gear on the manual gives the engine more power to go up the hills w/o overloading the engine or reducing the car's speed. I sure would be inconvenient if every time you went up a hill on the highway you had to manually downshift to keep the car at speed, and then reset the cruise control.

It has not been my experience that driving within the high rev vtech mode uses more gas. When I have taken trips of mostly highway driving, I have gotten some of my best gas mileage when the engine was in the upper vtech mode. I think the mode change allows the engine to breathe better, and perhaps allows it to achieve better gas mileage.