Making Sense of the Difference Between 4WD and AWD
Source: news.com.au
With Australians purchasing new cars at a record pace, a surge in the growth of SUV sales saw the category land fractionally behind the number of passenger vehicles sold during August. Which leads to a common, yet often misunderstood, question – what exactly is the difference between 4WD and AWD? In many instances, consumers are led to believe these two systems are the same. However, there is a notable distinction between the two, which will shape your driving experience.
FWD (front-wheel drive) and RWD (rear-wheel drive) vehicles rely upon a single axle to distribute power to move the car. Conversely, 4WD (four-wheel drive) vehicles depend upon a distribution of torque from the transmission going to all wheels at the same time. This transfer is done via a component called a transfer case, ensuring an even distribution. As a result, 4WD vehicles have added versatility – they are equipped for off-road driving, typically across terrain such as mud and rocks.
However, in some instances, like turning, having power supplied to all wheels is undesirable or simply unnecessary. To account for this, some 4WD systems can be controlled (activated/deactivated) through a central mechanism – a dashboard switch, or via a handle. When the system is off, the car effectively operates like a two-wheel drive vehicle. In 4WD vehicles where such controls are not available, they will permanently act as a four-wheel drive, but a differential is used to adjust the individual axle and wheel speed where necessary.
There are also controls which allow differential regulation of the system (either high or low), so that one can distribute the power in a non-equal fashion. In turn, these options can be used to either mitigate the effects of locked wheels, or make them act in such a manner.
Source: Subaru.com.au
On the other hand, the AWD (all-wheel drive) system is used across a wider variety of vehicles, particularly passenger vehicles but also ‘mini’ SUV’s. The other notable feature is that they are effectively in use all the time, and cannot be ‘deactivated’. In a mechanical AWD system, three differential gearboxes help to distribute the torque to the front and rear axle, and then each of the wheels. Meanwhile, electronic AWD systems use an engine control unit, as well as a myriad of sensors, to distribute the torque where it’s required.
This type of system is most suited to wet or slippery driving conditions, or in sporting applications where each wheel has a different level of friction with the ground. While not quite possessing the off-roading capabilities, or low-range driving associated with 4WD vehicles, general handling and weight distribution is considered to be superior, and one doesn’t need to adjust the system to calibrate it.
With that said, both systems do share one commonality – that is, they generally increase the weight of your vehicle, which in turn decreases your fuel economy.
If you have any questions, don’t hesitate to contact us.
Best wishes,
The Private Fleet Team
Level 2, 9 Help Street
Brian Smith says:
Hi
I am thinking of buying the entry model of a LEXUS NX 2000.
To further reduce the cost I’m considering the 2WD version as it is considered faster i.e. lighter and more fuel efficient.
What are you thoughts?
Regards
Brian Smith
September 26th, 2016 at 2:54 pm
Ged says:
1. I understood that in AWD, if one wheel had no purchase (ground friction), all power would be transferred to that wheel rendering the vehicle immobile. Is that not true?
2. The Mitsubishi Challenger has optional AWD, as well as RWD and 4WD
September 26th, 2016 at 5:44 pm
Bob Chantrell says:
4 years ago I purchased a new Subaru Liberty Station Wagon.
2.5 fuel injected Auto. Not turbo.
I agree with your summary with one exception.
We regulary return 800 plus to a tank of fuel. Best was on a interstate run which shower in excess of 900. This is by far the best for reliability and economy I have had from any of my cars.
I do not believe the AWD came at a dissadvantage at all. Just replaced the tyres at 77,000.
This is an often overlooked family SAFE car.
September 27th, 2016 at 5:50 am
Dave Conole says:
https://en.wikipedia.org/wiki/Four-wheel_drive specifically the Differentials section
September 29th, 2016 at 10:20 am