Quote: I can only guess that what is to follow is a direct result of not knowing much about turbos:
My understanding was that because a turbocharged engine will produce an equal amount of power more efficiently than a similiar N/A engine that there could potentially be a higher efficiency at highway speeds. For example, if it takes 100HP to keep my truck moving at 65MPH on the freeway (~2100rpm), the turbo'd engine will be able to produce that 100HP more efficiently using less fuel.
Is this inaccurate?
On the highway at a steady speed, you will have no boost. Your engine will be under vacuum just like a n/a engine. The turbo engine sees no benefits from the turbo itself in this scenario because you are just taking the turbo along for the ride. The only difference is the turbo engine may have a milder cam, resulting in better economy during normal driving. However the turbo engine may have a lower compression ratio, offsetting or partially offsetting the gains of the milder cam.
