Since compact SUV’s have been making quite a mark on the car market recently, every prospective buyer has forged a battle in his/her brain, 4 Wheel Drive vs All Wheel Drive (4WD vs AWD) and not knowing exactly the differences between the two. Don’t worry, we’ll make it as simple as possible and delve into only the essential technical details. Here’s everything you need to know:
Both the drivetrain types are primarily known for their ability to provide power to all the wheels of double axled vehicle simultaneously as well as their superiority to 2WD in rough and difficult terrains. The differences are evident in the way they transfer power to the wheel ends and their abilities to handle different terrains.
While both the drivetrains are different from a traditional 2WD, where the rear or front tires are powered while the other two move freely, they are both distinct from each other in a few ways:
The main factor differentiating 4WD in the battle that is AWD vs 4WD, is that it lacks a differential, and power goes from the transmission to a transfer case. The transfer case splits the power between the front and rear axle ensuring maximum torque to each wheel making it extremely adept at handling off road situations, and crossing near impossible terrain. 4WD used to be very basic, with a rudimentary lever that switches power from rear or front wheel drive to splitting the power between the 4 wheels. However, nowadays there are buttons or switches with multiple 4 wheel drive settings giving a fair bit of control to users and flexibility to the car’s capabilities.As amazing as 4WD cars are for off-roading situations, they also pose a few challenges. As all the wheels are powered separately, and evenly, all of them operate at the same torque as the others. This leads to certain difficulties as each wheel turns at the same speed due to even distribution of torque whereas while turning we need the inside wheel to turn slower than the outside one because the outside wheel covers more ground. This phenomenon causes the inside wheel to lose traction and spin freely, making forward movement inefficient, fuel expensive, and troublesome.
The AWD system is a rather recent technological innovation that is now being widely implemented in cars all over the world. The most basic layman’s definition of an All Wheel Drive car is ‘Permanent 4 wheel drive’ which means it is on all the time. The main factor that separates this from 4WD cars is the fact that in AWD, there is a differential between the front and rear axles instead of a transfer case that takes power from the transmission and uses it to split different amount of power between two wheels, or the front and rear axles. The torque is permanently split between all the wheels, and there is no lever, or buttons that switch the car’s drivetrain to 4WD or 2WD.While the older AWD systems were mechanical, and had 3 differentials used to split power, nowadays, it’s all computers that do the work. Sensors are present on each wheel monitoring traction levels, torque, and wheel speed and accordingly redistributing power where it’s needed. These systems are more versatile than older 4 wheel drive systems as they can detect the traction levels, and thereby split the power accordingly for example in off road conditions where each tire has a different amount of grip being experienced. This automated change in power levels increases the overall fuel consumption of AWD cars.
So while the 4WD cars offer extreme off road handling, providing grip and handling in all conditions, as well as having the option to switch off the system to improve fuel economy, the system itself adds a lot of weight to cars accompanied with the risk of forgetting to switch the system off leading to problems on a normal road. 4WD cars also have the disadvantage of not being able to reach high speeds as all wheels get equal power. The clear advantage of AWD is that it doesn’t need any work or knowledge to operate in off road situations as the ECU automatically detects loss in grip/traction and provides power accordingly to the wheels, making it suitable for all road conditions. However, this automatic system also increases the money spent on fuel and is not as efficient as the rugged, proven, and older 4WD systems. All-Wheel Drives also suffer from major problems in extreme off-road conditions that are handled with ease by 4WD systems.