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The number of gears in a standard gearbox typically ranges from 4 to 8, depending on the transmission type and vehicle positioning. The mainstream configurations for manual transmissions are 5-speed or 6-speed, with the 5-speed structure being more common and suitable for economy cars such as the Civic, while the 6-speed is mostly found in models focusing on performance or fuel economy like the Corolla. Automatic transmissions are mainly 6-speed, and high-end models may be equipped with 7-speed or 8-speed ones—for example, some Mercedes-Benz models use a 7-speed gearbox, while luxury cars like the Lexus LS460h are equipped with an 8-speed gearbox. Although continuously variable transmissions (CVT) theoretically have no fixed gears, manufacturers often simulate 6 to 8 virtual gears through the on-board computer to enhance the driving experience. Increasing the number of gears can optimize the smoothness of power output and fuel efficiency, but it also increases manufacturing costs and maintenance complexity. It is worth noting that commercial vehicles such as trucks, due to their high torque requirements, may be equipped with gearboxes with up to 16 gears, which is significantly different from the design goals of passenger cars.

Currently, there are indeed cars equipped with only a single-speed transmission on the market. This type of design is mainly applied to pure electric vehicles. Its core principle is to achieve direct transmission of motor power to the wheels through a fixed gear ratio, eliminating the need for multi-gear shifting as in traditional fuel vehicles. The advantages of single-speed transmissions lie in their simple structure, low failure rate, and low maintenance costs. For example, models such as Tesla and BMW i3 adopt this design, which can provide a smooth acceleration experience and fast power response, making them particularly suitable for urban commuting. However, due to the fixed gear ratio, vehicles may face limited top speed or slightly higher energy consumption when driving at high speeds. But the high-speed characteristics of electric vehicle motors (generally reaching more than 15,000 rpm) make up for the drawback of a single gear. For instance, the single-speed transmission of the Zeekr 001, combined with its four-motor architecture, can still achieve a 0-100 km/h acceleration time of 2.02 seconds. In addition, this design also reduces manufacturing costs. For example, economical electric vehicles like the BYD e5 control their selling prices by simplifying the transmission system. It should be noted that a single-speed transmission is not a technical flaw but an optimized solution tailored to the power characteristics of electric vehicles (wide speed range and instantaneous torque output). In the future, with the development of motor technology, its performance limitations may be further reduced.

The adoption of 20-speed transmissions in trucks is primarily driven by comprehensive considerations of power adaptability, fuel efficiency, and driving safety. Diesel engines have a relatively narrow optimal torque output range (typically 1000-2500 rpm), and the multi-speed design maintains engine operation within the efficient speed range through precise gear ratio spacing. For instance, the Fast 12-speed transmission utilizes a range selector to switch between low gears (1-6) for heavy-load starts or hill climbing and high gears (7-12) for cruising, effectively addressing the dilemma of "insufficient pulling power in high gears and excessive engine speed in low gears." Moreover, smoother torque transitions (e.g., reducing torque difference between adjacent gears from 200 N·m to 50 N·m) minimize drivetrain shock and prolong clutch life. For tractors hauling over 40 tons, multi-speed transmissions further optimize fuel consumption, with field tests showing 16-speed units achieving approximately 8% better fuel economy than 9-speed models. Notably, these transmissions typically employ a "main-and-auxiliary box" configuration where range shifts are executed via a preselector valve, eliminating the need to sequentially shift through all gears.

"373 gears" usually refers to a specific combination or numbering of gears in a car's gearbox or transmission system, where the number may represent the number of gear teeth, transmission ratio, or model identifier. Gears are the core components of a gearbox, enabling power transmission and speed change through the meshing of driving gears, driven gears, and idler gears. For example, helical gears, with teeth arranged at an angle, are quieter and transmit power more smoothly than spur gears, and are widely used in the gearboxes of domestic vehicle models. Gear transmission has advantages such as high efficiency (up to 99%) and compact structure, but requires regular lubrication to reduce wear. If "373" relates to the gear configuration of a specific vehicle model, it is recommended to consult the vehicle's technical manual or an authorized service center for accurate parameters. The precise design of the gear system directly affects the smoothness of the vehicle's power output and fuel economy.

Both 6-speed and 7-speed transmissions have their own advantages and disadvantages, and the choice should be based on actual needs. The 6-speed transmission typically features a wet dual-clutch design, offering superior cooling performance and higher torque capacity (e.g., 350Nm), making it ideal for driving scenarios prioritizing performance and durability. However, it requires regular transmission fluid changes (approximately 6.5 liters), leading to higher maintenance costs. The 7-speed transmission predominantly uses a dry dual-clutch design, with a more compact structure, smoother gear shifts, and marginally better fuel efficiency (e.g., 0.4L/100km reduction). However, its maximum torque capacity is lower (250Nm), and prolonged high-load operation may compromise heat dissipation and reliability. For stability and long-distance driving, the 6-speed is preferable; for urban commuting comfort and fuel economy, the 7-speed holds an advantage. Price-wise, the 6-speed transmission typically costs around RM10,000 more but eliminates the potential cooling issues associated with the 7-speed.