peak horsepower? low or high?

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i ask the question for this maximum horsepower is always an integral part of marketing ads by car manufacturer. if u go to vehicle specification you will notice the likes of 140 hp * 6300 rpm, 128 hp * 4300 rpm and sometimes the said vehicle belongs to the same category of displacement 1.8/2.5/3.0 but have difference only on peak horsepower high and low rpm. What difference will it make if the vehicle maximum/peak horsepower can be reached at a higher rpm as compared to the vehicle peak horsepower which can be reached at lower rpm example a 1.6 with 128 hp * 4300 rpm AND 1.6 140 HP * 6300 rpm ... thanks.

It all depends on what type of vehicle you will use the engine and what the purpose of the vehicle would be. For a daily driver, horsepower and torque in the midrange would be better than one that requires you to rev to 10K rpm. Typical cars now have a power curve that builds to it's peak at around 4k-6k rpm. Again for regular street use horsepower is less of a factor than torque. Because torque is what you need to move the car in stop and go traffic. What good is having 200hp*7500rpm and only 115lb-ft*5500rpm, you would have to rev the engine just to get it to move the car. If you just want to run the car for top speed then you want high rpm horsepower peak so that your car doesn't run out of steam with the increase in revs. But if you have a truck and you use it to haul stuff or even off road then you want low rpm torque and low to mid rpm horsepower peak, because that's where it would be of more use for the purpose of the vehicle.

Most vehicle ads just mention the horsepower and don't mention the rpm since most buyers get hypnotized by the horsepower numbers without considering how that power was attained. Hence, you have people that buy the S2000 and complain that they have to rev the engine to get any sort of torque from the motor to drive around town.