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The Difference Between AWD and 4WD

Everyone understands that vehicles have four wheels. When it comes to safety in inclement weather or issues with performance on a wet or icy roadway, people tend to seek out vehicles with All Wheel Drive or Four-Wheel Drive. However, not everyone understands the basic differences between these two and why one may be better or worse than the other.

Difference between AWD and 4WD

Basically, in today’s market the All-Wheel Drive and Four-Wheel Drive features mean there are different mechanical systems at work within the vehicle’s frame and under the hood. For a better idea of what this means, consider the following as a guide to all you need to know. 

Down to Basics: AWD vs 4WD

All-Wheel Drive uses a layout that moves the power of the vehicle from any tire that might be slipping to the other, hopefully better performing tires. This is with a front-wheel drive primary setup, so it allows the tires that are able to grip the road, provide traction and keep the vehicle moving forward with little or no issues despite the problematic terrain. This can be set in place and forgotten, and the vehicle will kick it into play as needed and then revert to front-wheel drive when the AWD is not a requirement. This system is found in cars and smaller car crossover SUVs. However, it is common to see the smaller car crossover SUVs boasting four-wheel, rather than all-wheel drive.

Four-Wheel Drive, in comparison, is primarily a rear-wheel drive setup. It has settings focused on low-speed, off-road work and is found more in trucks and bigger SUVs. A dual-range transfer case is usually included with this system to allow a low-range and high-range 4WD. 

Defining Dual Range Transfer Case for 4WD

A device that takes the power from the transmission and “transfers” it to the front and rear axles is considered a transfer case. This is important for 4WD because it allows low-range gearing so the torque output is amplified at low speeds to improve transaction for the vehicle. 4WD high is available for those who have some situations where higher speeds and lighter weights still need the 4WD option. Otherwise, there is also an option that comes very close to what is provided with AWD. That option is called full time 4WD. 

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Four wheel drive (4WD) Front-engine
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Four wheel drive (4WD) Rear-Engine

AWD means the System is On At All Times

Typically, the AWD system cannot be turned off. Instead, the system provides 90-percent of power to the front axle and 10-percent to the rear axle in optimal conditions. As the weather or road conditions deteriorate, the power split will change until the split can be as equal as 50/50. Traction is always monitored by this system, and the power will be adjusted as necessary within seconds of issues for one or more of the tires on the vehicle.

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Front-engined AWD

Comparison between AWD and 4WD:

 

AWD

4WD

Acronym   

It stands for ‘All Wheel Drive’.

It stands for ‘4 Wheel Drive’.

Definition

It has a central differential system and thus is designed to power all four wheels at the same time.

Depending on the type of the system and on the road conditions, it is designed to automatically adjust the power in the front and back wheels.

Gear

Only high range gearing.

Low range and high range gearing.

Weather

It does not help in running the car smoothly in snow and rains.

It helps to run the car smoothly in snow and rains.

Cost

It is expensive.

It is cheap.

Weight

It is light in weight and consumes less space.

It is heavy in weight and consumes space.

Types

It can be automatic or selectable.

It is part time or full time.

Engine power

The vehicles deliver 90% of its engine power to the front wheels. More engine power is diverted to rear wheels via viscous coupling, only when the front wheels start to slip.

It transmits all of its engine power to the rear wheels. The second speed option allows splitting the engine power equally between front and rear wheels.

Differential device

The option of central differential is available.

The option of central differential is inbuilt and is not available.

Advantages

  • Provides increased grip and control under all road conditions.
  • Gives sportier handling and traction to a broader range of cars.
  • Works all the time
  • Best traction in off-road conditions.
  • Can be turned off to improve fuel economy.
  • Proven, rugged technology.

Disadvantages

  • Reduces Fuel Economy.
  • Increases the weight and complexity of vehicles.
  • Not as good in extreme off-road conditions.
  • Adds weight and complexity to cars.
  • Can’t be used in all conditions.
  • More expensive than two wheel drive models.

Examples

Pontiac Vibe, Toyota Matrix, Subaru Legacy GT.

Suzuki SUVs (part time), Mitsubishi Montero (full time).

Preferences: Which One Would be Better?

There is no right answer to this question. It becomes a matter to consider with specific situations and usually even then comes down to the personal preference of the vehicle driver. If you tend to do more off-road travel, the best investment can be 4WD. However, for those who want better fuel economy while still feeling secure and knowing the vehicle is shifting power as needed, the AWD option is a great choice.

One factor to note is that people who have bigger trucks and SUVs typically have 4WD. This helps the vehicle handle the greater weight of the vehicle while still providing the best traction possible in any terrain or weather condition. This cuts down on the gas mileage you may be hoping for, but it typically gets you out of tough situations much more easily. 

When purchasing a new vehicle, it is best to sit back and determine what terrain you will regularly need to travel and what weather conditions will plague your commute or vacation time. Once those decisions are made, you can weigh the fuel economy versus the better traction in mud or over rocky terrain scenarios. This will allow you to pick the better choice of AWD versus 4WD for your daily use. Then, you get the fun of heading out to compare vehicles and find the new one that will grace your driveway in the near future.

Source: www.differencebetween.info, wikipedia.org