Yup more boxes = more drag = more gas at the same speed.I totally agree. I've found that if I stay below 73mph (3,900 rpm is the key more than the speed) my fuel mileage is stays steady. 73 (4,000 rpm) and above, it starts dropping. So, I fully expect a mileage hit with higher speed, but today showed me how much the boxes specifically, impacted the mileage . . . . because all the other potential factors remained the same.
Or put in layman's termsDrag increases as the square root of the speed, and the power required to sustain the higher speeds increases as the cube of the speed, read exponentially higher.
Hopefully I explained this, however; other "egg heads" are most welcome to comment.
Sent from my SM-A715W using Tapatalk