[solarguy]

Many good points already mentioned. I will add two minor ones.

1. Yes, diesel fuel contains more BTU per gallon, but a diesel engine with substantially higher compression is inherently more efficient than a gasser, all other things being equal. This is a direct consequence of Carnot efficiency. The stripped down version of Carnot efficiency says the higher the delta T (that is combustion temperature minus exhaust temperature) the more efficient, period. Higher compression produces higher combustion temps, all other things being equal. Less pumping losses was mentioned and is true also.

2. A semi has less surface area than a car, per pound. Quite a lot less. So even though they look as aerodynamic as a brick, there is less surface area to produce drag.


Finest regards,

troy