*Featured image source: www.westcoastauto.com
When purchasing a new vehicle, we usually come across these three terms – 2-wheel drive (2WD), 4-wheel drive (4WD) and all-wheel drive (AWD). These are actually the different types of drivetrain. Drivetrain is a group of components that powers a vehicle’s wheels.
The various types of drivetrains can make a huge difference when it comes to road conditions – driving in harsh weather conditions or on unpaved or rough terrain.
In this article, we take a look at the three aforementioned drivetrain systems and its differences.
2WD is the most common drivetrain system equipped on passenger vehicles. This drivetrain system means the engine powers two of the vehicle’s wheels.
Depending on the drivetrain set up, vehicles with 2WD are either powering the front wheels or the back – front-wheel drive (FWD)/rear-wheel drive (RWD).
Vehicles with a 2WD system are also generally lighter than vehicles with other drivetrain systems since additional components such as differentials are not required as opposed to 4WD and AWD vehicles which requires these components to distribute power across all 4 wheels. Additionally, vehicles with 2WD systems are cheaper to produce and have better fuel economy since the engine only needs to power two wheels.
As the term suggests, a “four-wheel drive” system splits power equally to all four wheels. 4WD are most commonly found on vehicles intended for off-road conditions such as steep hills, uneven and rough terrains.
Although providing greater traction, 4WD vehicles can be a little problematic when used on ordinary roads. This is because, when taking a corner, all four tyres will have to rotate at different speeds – the outer wheel has to travel a greater distance than the inner wheel while 4WD distributes power evenly across the 4 wheels. However, certain 4WD vehicles comes equipped with differentials gears which allows the wheels to turn at different rates but with the cost of reduced traction.
Modern 4WD systems also comes with the ability to work on a “part-time” basis. This means that the driver can manually switch between 4WD and 2WD according to the road condition. Even newer 4WD systems are designed to automatically switch between the two systems to provide optimal handling conditions without the need of human intervention.
2016 Volvo XC90 AWD System
Picture source: www.autoevolution.com
Although 4WD and AWD are often misinterpreted, there is one main distinction – 4WD is a drivetrain system that tries to send as much power to all four wheels as equally as possible for utmost traction while AWD is all about varying the amount of power to each wheel through various means such as differentials, transfer cases or electronically by brake vectoring (where the brakes are used to slow down a specific wheel due to traction loss).
Another factor which distinguishes AWD from 4WD is the type of vehicles they are equipped to. AWD are usually designed for road-going vehicles, such as sedans, crossovers and SUVs while 4WD is typically used on vehicles designed and built to handle rough terrains such as pickup trucks.
According to Consumer Report, “Subaru’s AWD system always directs at least 20-percent of the engine’s power to the rear, and it can direct a larger amount if needed”.
Most vehicles with AWD, are also equipped with a feature that is similar to the automatic function in modern 4WD systems – controlled by a computer system that automatically shifts power to whichever wheels need it most, giving the driver added traction.
To put it simply, AWD vehicles are better suited for sloppy road conditions, mud and looser surfaces like sand instead of rough and uneven terrain that is suited for 4WD vehicles.
In the end, each drivetrain system has their own unique approach and function in relation to road conditions and the driver’s driving habit.
The average driver will be suited better to a 2WD-based vehicle as it is designed to handle smoothly on regular road conditions while 4WD vehicles are suited for drivers who are adventurous and thrill-seeking – “offroaders”. AWD vehicles on the other hand, are designed for drivers who are looking for an adventurous driving experience without the need of being technical.
For an overview of all the mentioned drivetrains, watch the video below: