手动机械传动采用齿轮直接驱动，传动效率高，机械损耗小。因此，它可以说是理论上省油的变速箱。当然，这种节油变速箱必须基于对变速箱的精确控制（掌握换档正时等）

Manual mechanical transmission adopts gear direct drive, with high transmission efficiency and low mechanical loss. Therefore, it can be said to be a theoretically fuel-efficient gearbox. Of course, this fuel-efficient gearbox must be based on precise control of the gearbox (mastering shifting timing, etc.)

自动变速箱（at）、无级变速箱（CVT）和双离合器变速箱（DSG）属于自动变速箱。

Automatic transmission (AT), continuously variable transmission (CVT), and dual clutch transmission (DSG) belong to automatic transmissions.

自动变速箱（at）是指液压自动变速箱。它是由液力变矩器、行星齿轮和液压控制系统组成的自动变速箱。传动扭矩是通过液压传动和齿轮组合来实现的，传动效率低，功率损耗大。因此，这种自动变速箱耗油较多。但由于变速箱通过液压传递扭矩，冲击小，传动平稳。

Automatic transmission (AT) refers to a hydraulic automatic transmission. It is an automatic transmission composed of a hydraulic torque converter, planetary gears, and hydraulic control system. Transmission torque is achieved through a combination of hydraulic transmission and gears, with low transmission efficiency and high power loss. Therefore, this automatic transmission consumes more fuel. But due to the transmission of torque through hydraulic pressure, the impact is small and the transmission is smooth.

无级变速箱由两个直径可变的传动轮和中间套筒上的传动钢驱动。CVT可以实现大范围的无级变速，从而获得传动系统与发动机工况的佳匹配。因此，从理论上讲，它所能带来的燃油经济性是好的。然而，CVT的钢带传动效率无法与传统的手动齿轮传动机构相比，不能说它是省油的传动。由于钢带强度的限制，变速箱不能用于大扭矩的传动，因此发动机扭矩较大（大于300nm左右）时不适用。

The continuously variable transmission is driven by two variable diameter drive wheels and a drive steel on the middle sleeve. CVT can achieve a wide range of continuously variable speeds, thereby achieving a good match between the transmission system and engine operating conditions. Therefore, theoretically speaking, the fuel economy it can bring is good. However, the steel belt transmission efficiency of CVT cannot be compared with traditional manual gear transmission mechanisms, and it cannot be said that it is an fuel-efficient transmission. Due to the strength limitation of the steel strip, the gearbox cannot be used for high torque transmission, so it is not suitable for high engine torque (greater than about 300nm).

双离合器变速箱以手动变速箱为基础：双离合器自动变速箱由轴驱动，传动部分由行星齿轮驱动。动力传动原理与传统的手动变速箱相同，传动效率高，机械损耗小，但变速箱的控制比手动更精确，所以对于普通人来说，双离合器变速箱当然比手动变速箱更省油，它具有经验丰富的老司机，手动控制比自动控制更精确。在这种情况下，手动控制比DSG更省油。实际上，DSG是技术含量高、综合性能和经济性优越的变速箱。

The dual clutch transmission is based on a manual transmission: the dual clutch automatic transmission is driven by a shaft, and the transmission part is driven by planetary gears. The power transmission principle is the same as that of the traditional manual transmission, with high transmission efficiency and low mechanical loss, but the control of the transmission is more accurate than that of the manual transmission. Therefore, for ordinary people, the dual clutch transmission is certainly more fuel efficient than the manual transmission. It has experienced drivers, and the manual control is more accurate than the automatic control. In this case, manual control is more fuel-efficient than DSG. In fact, DSG is a gearbox with high technological content, superior comprehensive performance and economy.

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