Drag coefficient is a misleading and meaningless statistic to compare, which is probably exactly why manufacturers use it. The total drag of a vehicle is given

Drag coefficient is a misleading and meaningless statistic to compare, which is probably exactly why manufacturers use it. The total drag of a vehicle is given by its total frontal area, multiplied by the drag coefficient. And fuel economy is determined by total drag. The Ram has a much larger frontal area than the Prius, so it would have substantially worse efficiency even if the coefficients of drag were equal.