I've heard that idea for a long time and have wondered about it: drag (air resistance) is dependent on the square of the velocity and in highway cruising where

I've heard that idea for a long time and have wondered about it: drag (air resistance) is dependent on the square of the velocity and in highway cruising where you're not accelerating, overcoming drag is a huge part of energy expended. How can the engine be tuned to be so inefficient at lower speeds that it somehow gets better fuel efficiency at higher speeds? And if that was ever a thing with older engines, is it still a thing with modern fuel-injected engines that sense performance and adjust fuel injection to optimize?