Has anyone come up with the diefinitive physics on this question??
What is the question?
What question? Each different car, truck distance wind speed and direction in relation to the direction of travel etc. all are factors. It is just not possible to factor them all in. It is far easier just to measure it.
Physics is what it is. Our “laws” are simply mathematical explanations of the way the physical universe acts, explanations that we at that time believe we’ve “proven”.
Race drivers, teams, crews, and engineers all know they conserve fuel with a car either immediately behind them or (better) immediately in front of them. Cycling teams (I’m a former cyclist) know they can conserve energy and even go faster farther with a team member immediately in front or behind them. They can feel the difference…dramatically.
The formulae are a string of variables. But the physics is proven in every auto race and every cycling event. It’s real. And everyone who races has felt it and seen the difference it makes in their times. Myself included.