[sgtlethargic]

What's the "sweet spot" of a gas engine relative to mpg?

Let's say you use the Ecomodder calculator and estimate a certain car needs 40 hp to cruise at 60 mph. Theoretically, would a 40 hp engine get the best mpg? Or, is it where the torque and hp lines cross on a graph? The area under some curve? Wide open throttle?

The followup idea is to add a turbo for acceleration needs.

What do you think?

Thanks