For me it is very simple. If on the highway (in the top gear), it instantly responds to even slight throttle modulation and on level road it accelerates quicker than it decelerates when I take the foot of the pedal. If 65-80 is much quicker than 80-65, I am happy with the vehicle. Now if itcan accelerate briskly on slight uphill without shifting down, that is icing on the cake. Some cars are eager to accelerate while others need to be pushed to move. I presume horsepower, torque, gearing, weight need to be balanced. Some some car may have more horsepower but might not feel "quick" to me as the other which has less horsepower given everything else. Too simplistic?