Four-wheel drive is a broad term used to refer to vehicles with extra driveshaft performance and gear range for various off-road and terrain applications. The 4WD system can be full-time or on-demand, depending on the car, and the Auto 4WD is one of the variations of the 4WD system.
Generally, the terminology used by car manufacturers to market their vehicles can sometimes be confusing to the average person. On the flip side, the SAE International Standard JI952 recommends using All Wheel Drive to describe all types of 4×4, 4WD, and AWD systems on passenger cars and light trucks.
However, there are significant mechanical differences between the 4WD, AWD, and 4×4 systems, which we will explain below to help you figure out if an automatic four-wheel-drive vehicle is best for you.
So, what is auto 4WD? Let’s find out.
How Does the 4-Wheel Drive Auto System Work?
In an auto 4-wheel drive car, torque is concentrated on the rear wheels in ordinary driving situations. However, the transfer case features electronic sensors that monitor the rotational speed of the car wheels. They also detect any differences with the wheels spinning due to loss of traction.
Once the electronic sensors detect that one or more of the wheels are rotating faster than the others, the transfer case immediately locks in the front and rear axles together, activating the 4WD mode. This allows the engine power to be distributed evenly to the wheels to improve stability and regain traction.
The system engages and disengages itself automatically in seconds, with the driver hardly noticing. The advantage of auto 4WD is that it requires no manual input from the driver, unlike the regular 4WD system.
Additionally, auto 4WD cars, such as the Jeep Rubicon, are suitable for everyday use as it enhances the drivetrain to make driving on slippery and off-road surfaces easier and safer.
How Is Auto 4WD Different From 4WD?
Four-wheel drive, also known as 4WD or 4×4, is a drivetrain system that locks the front and rear axles together to power all four wheels simultaneously. There are two types of 4WD systems: full-time and part-time 4-wheel drive.
Full-time 4WD cars, such as the Land Rover Defender, feature a drivetrain that is permanently in the 4WD mode that gives them the ability to drive in any terrain and driving condition without any driver input. Additionally, the 4WD vehicles feature a ladder frame chassis that features a solid rear axle with an independent front suspension for stability.
This design makes the cars strong with excellent loading capacity allowing them to handle off-road conditions better and tow caravans and boats.
However, 4WD vehicles consume significantly more fuel because they are heavier, making them uneconomical for everyday use. Plus, the cars are expensive to buy, and the drivetrain costs more to maintain.
Part-time or manual 4WD vehicles are similar to auto 4WD, except that the driver has to engage and disengage the driving mode themselves. The 4WD car is ordinarily in 2H driving mode, and the driver engages the 4WD when they detect the car slipping on a low traction surface.
In contrast, an auto 4WD car uses sensors to activate the 4WD without the driver noticing, so this is more convenient for drivers with less driving experience.
On the other hand, a manual 4WD vehicle such as the Ford Ranger and Toyota Tacoma features a ladder-frame chassis similar to the full-time 4WD cars. It gives them the flexibility to go over rough terrain for extended periods and tow heavy vehicles while driving off-road.
Is All-Wheel Drive Better Than Auto 4WD?
An all-wheel-drive car features viscous coupling, multi-plate clutch systems, or center differential systems to automatically deliver engine power to the front or rear axles to maintain traction without driver input.
Like the 4WD system, AWD cars can either be full-time or part-time AWD, and each has its pros and cons.
The full-time AWD system like you would find on cars like the Subaru Forester, uses viscous coupling technology to maintain traction on all its wheels. On the other hand, part-time AWD is the most similar to auto 4WD when it comes to how it functions.
The system uses a multi-plate clutch system combined with electric sensors that monitor the rotational speeds of the wheels. The system temporarily engages the front or rear driveshafts accordingly to synchronize the wheel speeds.
Therefore, the part-time AWD vehicles, such as the Honda CRV, are typically in 2WD mode like the auto 4WD cars until any of the wheels lose traction. When this happens, the onboard computer activates the multi-plate clutch to regain traction.
What Is the Difference Between 4WD Auto and 4WD High and Low?
The 4H or 4-High setting gives you better control on snow and moderate off-road terrain. In 4H mode, the center differential is locked with the engine power split evenly between the four wheels. In 4-Low, the wheels rotate more slowly, and the car uses a low gear ratio to navigate soft or loose terrain and steep hills or declines.
However, the 4L mode does not enable better traction and is unsuitable for mud and snow driving conditions. Additionally, the 4L setting is similar to part-time 4WD on most cars, meaning you can use this setting to tow or to navigate rough terrain
Learn more about 4High vs 4 Low.
Is the 4WD Lock the Same as 4WD High?
In 4WD-Lock, the rear differential connects the rear axle side to side, so if one wheel slips, the other keeps moving to push you forward. While 4WD-Lock is ideally full-time 4WD—meaning you can drive at normal highway speeds on slippery surfaces—it is not suitable for high traction terrain.
On the other hand, auto 4WD cars are driven in 2H until the system automatically engages the 4WD when it detects the wheels slipping. The system disengages when the rear wheels regain traction, and there is generally no input from the driver.
Is Auto 4WD System the Best Choice for You?
As we discussed above, there are many variations of the four-wheel-drive system, and your choice depends on the terrain you will be driving your car on. Plus, most modern SUVs and Crossovers come fitted with the All-Wheel-Drive system that is more similar to Auto 4WD in how it functions.
However, Auto 4WD has a slight advantage over AWD in that it gives you the heavy-duty benefits of 4WD, such as the ability to tow and handle rough terrain.
Additionally, 4-Wheel Drive Auto is flexible where the car can engage the drive system automatically or manually with the driver input.
This is when other control features such as 4H, 4L, and 2H come in. The 4-High setting is not very different from Auto 4WD because it locks the front and rear axles together to help the car regain stability and traction on slippery surfaces.
While you can use 4-High at high speed, 4-Low is suitable for slow off-road driving such as rock crawling, towing off-road, or slogging through deep snow and sand. However, 4L is strictly slow driving and is unsuitable for slippery roads and high traction surfaces such as dry pavements.