What is the difference between a four-speed gearbox and a five-speed gearbox?

Usually the fourth gear of a four-speed gearbox is a direct gear, that is, the speed of the gearbox output shaft is the same as the engine crankshaft; the fifth gear of a five-speed gearbox is called an overdrive, which is the speed ratio of the gearbox output shaft The engine crankshaft speed is even higher.
When introducing a certain model, the torque and power in its technical parameters are usually the maximum torque and maximum power. The power and the corresponding speed indicated on the engine nameplate are called rated power and rated speed. The rated power is generally less than the maximum power (the maximum output power is also called instantaneous power, or peak power). The output power of the engine has a great relationship with the speed. With the increase of the speed, the power of the engine also increases, but after a certain speed, the power shows a downward trend.
The maximum torque generally appears in the middle and low speed range of the engine. As the speed increases, the torque will decrease instead. For family cars, the greater the torque, the better the acceleration; for off-road vehicles, the greater the torque, the greater the gradeability; for trucks, the greater the torque, the greater the weight of the car. In the case of the same displacement, the greater the torque, the better the engine. In the same car, the lower the gear, the greater the torque-the first gear has the maximum torque during normal driving, and the torque in reverse gear is greater than the first gear.
The quality of a car needs to be comprehensively evaluated in terms of its power, economy, safety, comfort, and cost-effectiveness. It is difficult to say its pros and cons from a few indicators alone.