What exactly is the difference between a 4-wheel drive system and an all-wheel drive system?
On the surface, away from using terms such as “differential” and “torque,” the difference is rather simple: 4-wheel is for off-roading, while all-wheel is for pavement. Let’s take a closer look at what makes these two drive systems unique.
The 4-wheel drive system, common in many trucks and all-terrain vehicles, is designed to give each wheel the same amount of power. This helps propel your vehicle over terrain where all the wheels may not remain in contact with the surface. This is great for driving on rough, uneven terrain, such as unpaved roads, or where the roads may be covered with snow or mud.
The all-wheel drive system, popular on some street-only vehicle models, is designed to send each wheel the necessary amount of power to spin the wheel while maintaining its grip on the road surface. For example, if the rear passenger side wheel slips a bit as you make a turn, the system senses this slip and sends more—or less—power to that wheel to stop the slippage and improve grip. This is a great feature when road conditions are wet or driving across gravel, leaves, etc. An all-wheel drive system cannot be turned on and off.
Blurring the Lines
There are unique differences between these two systems. The terms are often accidentally interchanged and innovations like “limited slip differential” for example, can make one system sound just like the other. Plus, the classification of different types of vehicles—SUVs, All-Terrain, Trucks, Crossovers—and their associated drive systems complicates the topic even more.
Let’s take a quick glance at the “limited slip differential” in a 4-wheel drive system.
If all four tires are always getting the same amount of power, that isn’t always good for you under certain circumstances, like attempting to make a turn. All power to all wheels all the time makes turning, during which the outside wheels should be rotating faster than the inside wheels, problematic. Your vehicle can lose traction, which defeats the purpose of the 4-wheel drive. The limited slip differential sends power to the wheels with the most grip and helps your vehicle maintain traction and control through situations like this.
You can now see how easily 4-wheel drive can be confused with all-wheel drive.
All-wheel drive systems, meanwhile, don’t supply the same level of power as 4-wheel drive systems, which is understandable as it is designed for smoother, paved surfaces and for use at higher speeds. It is not intended for off-road use or uneven terrain, like 4-wheel drive systems.
So, again, it boils down to the basic principle: Off-road for 4-wheel drive. On the road for all-wheel drive.
One Last Thing
Remember that no matter the type of drive system your car has, ice is ice, and tires still don’t get traction on ice. So, drive safely and smartly, especially when the possibility of ice on roads exists. In inclement weather, always leave yourself extra time for traveling, drive slower to account for poor road conditions, and be considerate of other drivers.