All true, except for one thing. Tq can be manipulated by gearing. Knowing that Tq is the only thing that will increase acceleration (except for lowing mass), one could just use larger and larger gear ratios to get more acceleration. The problem with this is what I was getting at above. More gearing makes more acceleration, but at a lower speed. Above I defined and proved why increasing hp is what you want to do if you are interested in increasing acceleration at any given speed. Obviousely increasing engine tq at a given engine speed will increase engine hp. However, engine tq does not move the car. The tq at the wheels does, which is engine tq multiplied by overal gearing. This makes engine tq meaningless without knowing the engine speed that its made at (or, more importantly, vehicle speed). Hp is different. Hp gets to the wheels the same no matter what the gearing is (ignoring insignificant changes in losses). This is why hp is a better measure for acceleration if you want a specific vehicle speed operating range. 300 ehp, 250 etq will accelerate a car just the same as 300 ehp, 350 etq. You just have to set the gearing so that you get the same wheel tq for each car.