As you surely know, most cars these days have four wheels. So why do people distinguish between all-wheel drive and all-wheel drive when four-wheel drive clearly means you’re driving all of them and vice versa? Despite the confusing names and some historically confusing usages, there is a meaningful difference between four-wheel drive (4WD) and all-wheel drive (AWD).
What does 4WD mean?
Before diving into the specifics, it’s important to understand the basics of each system. First, what is a four-wheeler? Often written as 4WD, but also denoted 4×4, an all-wheel drive system does what it says: Its powertrain is capable of sending power to all four wheels. 4WD systems also often have a gearshift box, which the driver must control via an auxiliary gearshift knob or electronic rotary knob, providing a low range for better road coverage and a high range for improved gear shifting. on Highway. The transfer case, while indicating a “true 4WD” system, is strictly not required to qualify as 4WD. All-wheel drive can be full-time, meaning all four wheels are powered at all times, or part-time/on-demand, where power is primarily sent to one axle (mostly). as always in the rear with a 4WD vehicle) until the driver selects the other axle for all-wheel drive. Increasingly, some 4WD vehicles can do this automatically (4A or Auto mode).
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What does AWD mean?
All-wheel drive or AWD, like 4WD systems, can also deliver engine power to all wheels. Likewise, AWD systems can be full-time or part-time/on-demand. However, very few people trust the driver to drive a four-wheeled vehicle. It is most common for AWD vehicles to be powered by one axle (typically the front in this case), until the vehicle senses or predicts wheel slip and transmits power to the other axle. respectively. Those with full-time drive can also vary the amount of power to the front and rear (this is common in rear-wheel drive vehicles, especially luxury and performance-oriented cars). capacity). However, unlike 4WD systems, AWD systems typically don’t have a gearshift box that the driver can use to choose from an extended range of gears for off-road and off-road use.
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Technical or Marketing Terminology Speaks?
Complicating matters, however, is that the descriptions of 4WD and AWD systems do not quite match how the terms are used, especially by the marketing branches of vehicle and part manufacturers. In practice, especially in the United States since the 1970s, the term AWD refers to the permanent drive sent to each wheel, but not the use of a transfer case. Four-wheel drive, on the other hand, is used to refer to part-time or on-demand systems that use a transmission. Furthermore, although the line has faded considerably over the last decade, AWD systems were previously marketed for primarily road-use vehicles, while 4WD systems were marketed for vehicles use significant terrain.
AWD vs 4WD: The Difference
Another factor that sometimes distinguishes a 4WD system from an AWD system is the type of differential used. In AWD systems, especially AWD systems intended for sportier use, it is common to see not only the difference on the front and rear axles, but also the center differential between the front and rear axles. . This second center differential is often overlooked on 4WD systems, especially those used only in off-road situations. Again, this is not a requirement for a system to be considered AWD versus 4WD, but it could be a contributing factor.
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Does an assignment case really matter?
Considered by many to be one of the key distinguishing factors between four-wheel drive and all-wheel drive vehicles, the transmission is an additional range of gearshifts, often divided into the high range and the low range. . This additional gearshift allows the wheels to spin more slowly at a given engine speed, enhancing driver control and torque available to maximize off-road capability. All-wheel drive systems typically do not have a transmission and are therefore generally unsuitable for extreme off-road situations. Therefore, to answer the question of whether the shift case is really important for a 4WD or AWD vehicle, it’s important to consider the vehicle’s use case.
Electric four-wheel drive system
For electrified vehicles, including full EVs as well as some crossbred, much of what you read above is not in any way applicable. Instead of relying on a differential or transmission to send power to the secondary shaft, just an additional electric motor is needed to power the secondary shaft. Eg, Toyota RAV4 Hybrid and RAV4 Prime whose front axle is powered by a combination of an electric motor and a gasoline engine, while the rear axle is powered solely by its own electric motor. They work together thanks to the magic of computers, but are not mechanically related. All-wheel drive tram The analogy relies on separate electric motors powering each shaft. The Rivian R1T and R1S Take it a step further by powering each wheel individually by an electric motor.
Ultimately, which do you want and/or need?
Your use case can help you determine if 4WD or AWD is right for you. If you plan to go through rough terrain, including rocks, mud, deep sand, etc., you’ll want a 4WD vehicle. Those looking for better traction and enhanced stability in inclement weather will often be better off with an AWD vehicle.
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