Also, drag scales with the square of the velocity [1], and a semi is a helluva slower than a racing supercar. --- [1] drag = 1/2 x air_density x frontal_area

Also, drag scales with the square of the velocity [1], and a semi is a helluva slower than a racing supercar. --- [1] drag = 1/2 x air_density x frontal_area x drag_coefficient x velocity^2