Team AckodriveJun 6, 2022
Automotive terminologies can be confusing, especially when buying a new car. If you are in the process of purchasing a Sports Utility Vehicle (SUV), you may have come across a couple of technical terms: all-wheel drive (AWD) and four-wheel drive (4WD). Both the terminologies may seem similar, but they are not. So, how is all-wheel different from four-wheel drive? Read ahead as we divulge more details on AWD vs 4WD.
The terms all-wheel drive and four-wheel drive can be confusing as both mean the same—driving all four wheels. Yes, both systems can drive all the wheels of a vehicle. However, there is a difference in the way they operate. The below points will give you an idea about the key difference between all-wheel drive and 4-wheel drive.
AWD is a full-time system that constantly drives front and rear wheels.
4WD is a part-time system wherein the driver can choose to engage the drive to the front and rear wheels.
Refer to the table below to understand the significant differences between all-wheel drive and four-wheel drive.
|Parameters||All-wheel drive (AWD)||Four-wheel drive (4WD)|
|Working principle||It sends power to the front and rear wheels all the time.||The driver can engage the system to deliver power to the front and rear wheels.|
|Power transmission||Generally, it uses a center differential to distribute power to the front and rear wheels.||It makes use of a transfer case to distribute power to all the wheels.|
|Power delivery||The system can compute which wheel needs how much power and deliver a variable torque to each axle as per the road condition. It all happens without any inputs from the driver.||The system sends an equal amount of power to the front and rear wheels.|
|Application||Suitable for SUVs and crossovers driven on varying road conditions. Also ideal for high-performance vehicles for superior handling and road grip.||Best suited for off-road SUVs or vehicles driven in extreme off-road conditions with very low traction.|
|Flexibility||The driver cannot select between the AWD and 2WD modes.||The driver can turn off the 4WD system and choose the traditional 2WD mode.|
|Fuel efficiency||Lower than 4WD.||Higher than AWD.|
As the name suggests, all-wheel drive (AWD) is a drivetrain that sends power to the front and rear wheels of the vehicle. Further, there are two AWD types: one constantly sends power to all the wheels, and the car manufacturers generally call it full-time all-wheel drive.
The second type of AWD system sends power to only two wheels, but when the situation demands (less traction), it automatically transmits power to all four wheels. Hence, it is also called an automatic AWD system. Due to the variation in torque supply, all-wheel-drive cars are suitable for on-road driving.
The below points will explain the working mechanism of an AWD system in a car.
Both the full-time and automatic (part-time) all-wheel-drive system works without any inputs from the driver.
It distributes the power via a centre differential. That means the power is directly transmitted to the centre differential, which then splits the torque to all four wheels.
A full-time AWD system powers all four wheels at all times. However, if the road is slippery or there is less traction, the system calculates and distributes the power accordingly.
By default, the part-time AWD system drives only two wheels. It could be front or rear wheels, depending on the make and model.
When the road is slippery and there is a need for more traction, the system automatically sends power to all four wheels.
The automatic all-wheel-drive system uses electronic sensors to detect the loss of traction and the computer onboard controls the power transmitted to each wheel.
To give you a better idea, let's take an example of an AWD car. When driving on highways with ample traction, the part-time AWD sends power to only two wheels (front or rear). However, when you hit a bad patch of road, the system detects the loss of traction and provides power to all the wheels. Here, the computer makes all the adjustments, and there is no human intervention.
In a full-time AWD system, the car is always in all-wheel-drive mode. That means all four wheels constantly receive power. However, when driving around a corner, the system detects that the outer wheels need more traction than inner wheels and adjust the power delivery accordingly. The same applies when you are driving on a slippery road. The system sends more torque to the wheel, which has less traction.
Here are some of the benefits of an all-wheel-drive system in an automobile.
One of the main advantages of AWD is that it doesn't need any driver inputs to engage the system.
It is an intelligent system that can detect the loss of traction and send power to that wheel.
AWD improves the handling of the vehicle due to the varied torque supply to the wheels.
It works in varied road conditions such as wet/slushy roads, snow and also light off-roading conditions.
Below are the disadvantages of AWD.
All-wheel drive increases the cost of the vehicle due to the complexity of the system.
AWD is not suitable for serious off-roading as the driver has no control over the system.
All-wheel drive also decreases fuel economy.
Four-wheel drive (4WD) is a traditional and straightforward system when compared to AWD. It sends an equal amount of power to all four wheels when engaged. Yes, a 4x4 car requires driver inputs to drive front and rear wheels. A 4WD system transmits power to the wheels via a transfer case that acts as a locked differential.
A four-wheel-drive vehicle is best suited for extreme off-roads as all the wheels spin at the same speed. So, whichever wheel has traction can get the car out of a tricky situation. Some 4WD vehicles also come with high and low range gear, which the driver can select.
Refer to the below points to understand the working mechanism of a 4-wheel-drive system.
Similar to AWD, the four-wheel-drive system transmits power to all four wheels.
In a full-time 4WD car, all the wheels receive power continuously.
In some vehicles, the driver may have the option of controlling the ratio of power sent to the front and rear axle.
In a part-time 4WD (Four-wheel drive) system, the vehicles run on the 2WD mode by default.
If the traction is too low, the driver can engage the system by means of a lever or button.
Some systems also allow the driver to lock the differentials for extra traction.
To understand the working of 4WD even better, let's take an example of a 4x4 SUV. Let's assume that the vehicle has a part-time 4x4 system. When you drive the SUV on the road with good traction, it is in its default mode, which is two-wheel drive. Engaging 4WD on paved roads is not recommended as it locks the differential, and all four wheels travel at the same speed.
Driving on corners becomes difficult with 4WD engaged, as the vehicle may lose traction due to all four wheels spinning at the same rate. Hence, four-wheel drive must be employed only when required.
If you are into extreme off-roading, you can manually engage the system and choose high or low gear. The low mode can be helpful in extreme off-roads as it provides more torque to all four wheels. The high mode should be sufficient for light off-roading.
Here are the advantages of the 4-wheel-drive system in a car.
The 4WD system is rugged and can easily handle extreme off-road conditions.
It allows manual control of the system. Hence, the driver can use it as and when required.
A four-wheel-drive system provides more pulling power than an AWD car.
Modern-day vehicles come with more refined four-wheel-drive systems. Hence, the driving experience is not hampered.
4WD SUVs make extreme off-roading an easy task, and they can also handle bad roads.
Below are some of the disadvantages of four-wheel drive.
A four-wheel-drive system results in stiffer ride quality when compared to a 2WD vehicle.
It increases the cost of the vehicle. The maintenance costs are also on the higher side.
The four-wheel-drive also hampers the fuel economy.
If your driving majorly involves on-road and occasional off-roading, an AWD vehicle is a sensible choice. If you are looking to buy a mid-size SUV or a crossover for daily commutes, all-wheel drive is more than sufficient.
If you are an off-road enthusiast and extreme off-roading is on the cards, you can go for a 4x4 vehicle. They are rugged and can pull more load than an AWD vehicle. However, remember that a 4x4 SUV is not an ideal daily driver, so make an informed decision.
Also, read: How to buy a car through ACKO Drive?
An AWD car delivers lower efficiency than a 4WD vehicle. It's because, in an AWD system, the power is constantly transmitted to all four wheels, and the engine has to work hard to keep up with power demand.
Whereas in a 4x4 car, the system is engaged only when it is necessary. So, by default, the vehicle runs in two-wheel-drive mode, which consumes less fuel. However, do note that AWD/4WD cars are less fuel-efficient when compared to traditional two-wheel-drive vehicles.
Here are some of the most commonly asked questions and their answers related to all-wheel-drive and four-wheel-drive cars.
Is an AWD car as good as a 4WD car for off-roading?
A four-wheel-drive vehicle is better than an all-wheel-drive car when it comes to off-roading. The four-wheel-drive system is rugged and more efficient when it comes to handling rough terrains.
Is an AWD/4WD car safer than a two-wheel-drive vehicle?
The safety of a vehicle depends on its safety equipment, the road conditions and the driving style. Hence, one cannot conclude that a 4WD/AWD is safer than a two-wheel drive car. However, a car with an all-wheel/four-wheel drive can get away from tricky situations as it has better traction than a 2WD car.
Are all SUVs equipped with a 4WD/AWD system?
No, not all SUVs come with AWD/4WD systems. Only a few models in the SUV segment come with a four-wheel drive or all-wheel drive drivetrain. While buying an SUV, do check the specifications of the vehicle to determine the drivetrain.
Is a 4x4 car different from a 4WD vehicle?
No, 4x4 and 4WD are the same as they feature the same drivetrain. Both types of vehicles come with a system where it delivers equal power to all four wheels.
Is a 4WD car good for snow-covered roads?
Yes, four-wheel-drive cars are suitable for roads covered in deep snow. The driver can manually engage 4WD and also select high or low range. The low range allows the vehicle to crawl up steep hills.
Does an AWD car consume more fuel?
An all-wheel-drive car consumes more fuel compared to a traditional 2WD vehicle. Since the AWD system constantly relays power to the front and rear wheels, the engine must work at its maximum capacity. Hence, AWD vehicles are less fuel-efficient than 4WD and 2WD vehicles.
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