4WD vs AWD
Four-Wheel-Drive versus All-Wheel-Drive
A common question amongst SUV buyers is, “What is the difference between a Four-Wheel-Drive system and an AWD, or All-Wheel-Drive, system? And which one is better for my needs?”
If you look at the current Toyota range you will notice that the Rav4 includes some AWD models alongside the two-wheel-drive models, while the Hilux, Fortuner, Prado, FJ Cruiser, Land Cruiser 200 and Land Cruiser 70 series all have 4x4 models in their ranks. Lexus is the same, with the LX featuring 4x4 and the other SUVs being either two-wheel-drive or All-Wheel-Drive.
If you have a look at which models feature 4x4 you will deduce that it is the term for the more rugged and off-road capable vehicles, while AWD is used for those cars that are more at home on tar, gravel roads or light off-road use.
So what is the technical explanation? While AWD and 4x4 technology has changed over the years and the line between the two has become blurred, an acceptable explanation follows below.
The most accepted use of the term AWD is for cars with systems that drive all four wheels all of the time (permanently).
In addition, an AWD system does the thinking for the driver without driver-selected options. Instead, a computer is constantly monitoring inputs such as wheel traction and torque distribution so that it can best send torque to where it is needed, and even brake wheels that are spinning more than they should be. AWD vehicles do not have a transfer-case with high and low range, nor do they have lockable differentials.
AWD vehicles are designed for normal road use with occasional gravel or dirt road use and mild off-road use. They are particularly effective in slippery, low-traction situations such as in heavy rain and wet roads, gravel roads or in snowy or icy conditions.
Because the AWD systems in AWD vehicles are permanently engaged, they are able to respond instantly when they are needed, such as when a car begins to slide while cornering on a wet road, helping the driver and vehicle to recover control before it is too late. This is a significant advantage of AWD vehicles, and in this way, AWD is an effective safety tool.
The 2019 Toyota Rav4 narrows the gaps between AWD and 4x4 by featuring multiple drive modes such as ‘Mud & Sand’ and ‘Rock & Dirt’ for improved AWD performance.
4x4 or Four-Wheel-Drive refers to vehicles that have a manually selectable drive system. For standard driving on tar roads, most of these vehicles are driven by the wheels of one axle, usually the rear one, and it is up to the driver to select another mode, be it four-wheel-drive High (referring to high-range, for normal road speeds but on low-traction surface) or 4-wheel-drive Low (low-range, for low-speed driving, such as on rocks).
In a 4x4 mode, a fixed amount of torque is sent to each wheel, and because of this the 4x4 mode can’t be used on tar roads, where there is excellent traction., Doing so will casue damage to the differential.
The definition isn’t an exact science, though, and many 4x4 enthusiasts would argue that for a vehicle to be classified as a ‘4x4’ or ‘4WD’, it must have a low-range transfer case for engaging ‘4-low’. This is the case with the Toyota range, where all of the 4x4 vehicles, including the Land Cruiser range and the Hilux/Fortuner range feature part-time, selectable 4x4 with low-range. 4WD vehicles will also have at least one differential that can be locked, be it mechanically or through computer-controlled systems.
4x4 vehicles are also more rugged than AWD vehicles, with heavy-duty drive train, suspension and chassis components as well as high ground clearance. This means that 4x4 or 4WD vehicles are specifically designed and equipped to go offroad and tackle difficult off-road obstacles without damaging the vehicle. They are often built to carry a substantial load, too, be it for work purposes or so that they can be equipped for expeditions and carry the necessary equipment.
Some 4x4 vehicles feature an ‘Auto’ mode that allows them to act much as an AWD vehicle, where the vehicle’s systems will detect when 4WD would be advantageous for the conditions. Other vehicles have a 4WD setting that can be selected where the central differential is not locked, so that it can be driven on tar roads without damaging the drive system.