power measured in a straight line = (force x speed). Hence 1 HP = 550lbs x 1ft/sec = 550ft-lbs/sec. In this case, the "ft-lbs" in the numerator is actually "work", where (work=force x displacement)

torque is the rotational equivalent of force. As mentioned earlier, it is measured by the force (lbs) exerted along a given radius (ft).

the measure of torque in the English system is actually ft-lbs/radian but since radian is dimensionless, this simplifies to ft-lbs. To differentiate it from Work=ft-lbs, torque is quoted in "lb-ft".

rpm is the rotational equivalent of linear speed. Since power=(force x speed), rotational power = (torque x rpm).

BHP (brake horsepower) came from the output measured on a "brake dynamometer".

the engine torque is transformed by the drivetrain and tires into linear force onto the road surface, as the vehicle goes down the road. Along with this transformation, there are frictional losses

this linear force exerted by the driven tires then determines linear acceleration of the vehicle (force = mass x acceleration) - the higher the force (from the torque), the higher the acceleration.

with the vehicle at constant speed, the linear force exerted by the driven tires equals the total of the aerodynamic & frictional drag forces. The frictional drag increases about linearly with vehicle speed. The aerodynamic drag however, increases with the SQUARE of the vehicle speed.

since power = force x speed, the power required to defeat aerodynamic drag is then proportional to the CUBE of the speed. This means that you need EIGHT TIMES (i.e., 2 cubed) more power just to double your top speed.

the moral of this long-winded discussion is that torque is responsible for acceleration, and power is responsible for top speed. But the important thing is that you get diminishing returns from increases in power, since the bulk of it gets used for defeating aerodynamic drag, which increases dramatically with speed.