Macgyver, you are correct. 172 Driver should have said that the speed for a jet powered aircraft to achieve best ** RANGE ** is at approximately Vmd x 1.32, and no reference to Vy at all. This would be for the powered situation, not for gliding. I can’t seem to find an explanation for this 1.32 number. Max range occurs when the ratio V / Drag is at a maximum, which further requires the ratio Cl^.5 / Cd to be a maximum. Perhaps this further simplifies to approximately 1.32 Vmd. Various assumptions apply, such a thrust output and fuel flow is linear with speed, and the drag polar is parabolic (no mach/compressibility effects).
Smokey and Bookworm, thanks for your contributions. I always learn from your contributions.
Hawk