Car manufacturers are constantly skewing the lines between 4WD and AWD systems with clever marketing strategies and all sorts of unique and confusing names like 4Motion, Easy-Select, Super-Select, On-Demand etc. There is great uncertainty about the differences between AWD and 4WD and it is becoming increasingly harder for consumers to decide which option will best suit their needs. This article discusses the pros and cons of AWD vs 4WD and how effective the correct tires are, particularly in snow and icy winter driving conditions.
For snow driving conditions an AWD with good winter tires should perform just as well as a 4WD since most modern AWD have advanced electronic traction aids to assist the driver. These electronic aids manage and automatically adjust the torque split accordingly, thus making them very capable in snow and ice driving conditions, with less driver input required. Many traditional 4WD vehicles are more basic since they are better suited for heavy off-road conditions where complex vehicle electronics are not favored. Modern 4WD Utes and SUVs are, however, becoming more sophisticated and incorporate various electronic aids (standard since 2012) to assist the 4WD system in snow, mud and other challenging driving conditions. The key to safe snow driving is to adjust your driving style accordingly and fit winter tires for good traction in snowy conditions.
If you live in a part of the world that gets regular snowstorms throughout winter season then an AWD with good winter tires will be a sensible option. Select your vehicle wisely since many AWD systems function better than others due to their sophisticated traction control and electronic systems. Do not become overconfident with an AWD by driving as you would a front or rear-wheel drive vehicle in dry conditions. Contrary to popular belief, AWD and 4WD do not assist much with turning and stopping abilities. Research shows that this is a high cause of the majority of snow-related accidents.
Understanding the unique differences between 4WD and AWD is key in deciding which option is best suited for your application. The simple explanation is that there are 3 basic types of off-road vehicle configurations.
- Non-Permanent 4WD
- Permanent 4WD
There are variations of each type, however we do not need to get into the technicalities of each system too much since that is outside the scope of this article.
With this drive-train configuration, the power is always split between the front and the rear axle by means of a transfer case. Most have low range functionality. Many have a center diff-lock which can be engaged manually. Many modern 4WD vehicles make use of traction control or rear diff lockers for heavy off-road conditions. The drive-train can never be removed from 4WD mode and put into 2WD.
These vehicles have 2H/4H/4Lo functionality which means the power is normally sent to the rear axle in 2H mode for daily driving on a variety of surfaces. 2H also returns decent fuel economy since there are fewer drive train components involved in propelling the vehicle. Center diff-lock (4H) can be engaged and power can be split evenly between the front and rear axles. The drive-train mode is decided by the driver based on driving conditions so it important for the driver to be informed of the correct mode for each driving surface. Non-permanent 4WD has low range (4Lo) functionality for conquering challenging off-road conditions. Modern 4WD Utes usually have a rear diff locker or Traction control for difficult off-road driving conditions.
This system is permanently in 4H mode and cannot be changed to 2H where only the rear wheels are propelled. Some manufacturers incorporate a center diff-lock function which allows the driver to manually lock the front and rear driveshafts in place to propel as a single unit. Most traditional AWD do not have Low Range (4Lo) functionality. AWD is usually managed by a computerized system which controls the power split ratios. Power is fed to each wheel and certain vehicle AWD systems allow power splits to be adjusted on the fly by the driver i.e. 50/50% or 70/30% split etc.
Other AWD systems function automatically and adjust the power splits once the computer senses traction is lost on either front or rear axles. Manufacturers make use of various torque splitting methods such as torsion splits, viscous coupling or electronic clutch mechanisms etc. Each has their advantages and disadvantages.
Is AWD As Good As 4WD in Snow And Ice?
AWD can be just as capable as a 4WD in snow, ice and other slippery driving conditions if the correct tires are fitted and driver style is adjusted. Studies show that only a small percentage of AWD drivers equip their vehicles with winter tires. This single upgrade can greatly improve your safety in snow driving, even in a 2 wheel drive vehicle. Do not make the mistake to overestimate the capabilities of your AWD since it is the inability to stop or turn fast enough which causes most accidents in snow driving conditions.
A Four Wheel Drive (4WD) is optimized and designed for challenging driving conditions like rock-climbing, fording deep rivers, and conquering steep hills with loose, low traction surfaces. The fact is that many 4WD owners seldom need this extreme capability that a 4WD offers unless you are a serious off-road enthusiast.
With that being said, in many cases, an AWD vehicle does not have the high ground clearance offered by a 4WD UTE or SUV with Permanent 4WD. This means that when snow conditions get really bad your AWD might not have enough clearance to plow through thick snow and you might find yourself bogged. There is very little benefit of all four your wheels turning without enough traction or ground clearance to clear the obstacle.
AWD Advantages And Disadvantages
|AWD Advantages||AWD Disadvantages|
|The vehicles traction is governed and managed automatically||Most modern AWD Cannot drive in 2H if a drive shaft breaks, leaving you stranded.|
|AWD requires less driver input maintain traction across a variety of road surfaces.||More expensive to repair|
|Can drive across a mixed traction surface such as half snow and dry tarmac roads|| More drive-line components to service resulting in higher service |
|Permanently engaged in 4H mode for superior traction||More sophisticated drive-line systems which increases initial purchase cost|
|Many manufactures allow the driver torque splitting options by manually flicking a button|
|Much better control and traction over 2WD front and rear wheel vehicles in snow and other low traction surfaces|
|More even tire wear compared to rear and front wheel drive vehicles|
|Gives you more confidence to drive faster (55-65+ MPH) in a variety of conditions without concerns of damaging the drive-train system.|
Is AWD Safer in Snow?
Most 4WD vehicles do not handle as well as AWD systems in a variety of mixed wet and dry conditions. For example, you cannot leave a 4WD in 4H on a dry tarmac road that still has patches of wet ice and snow around since the drivetrain will succumb to drive train or axle binding. An AWD will have the ability to adjust to those conditions since the axles can operate independently and the system is managed by an intelligent electronic computer and sensors. This is when the transfer case and transmission lock up due to the high torque that gets built up on the inside of the transmission causing major damage to drive train components like drive shafts, u-joints, and diffs. 4WD is designed for more challenging, driving conditions like rock crawling and climbing out high uneven hills with deep ruts etc. 4WD vehicles will not do well in combinations of wet and dry roads where certain parts of the road have good traction and other parts are slippery due to snow or ice.
Are Snow Tires Better than AWD?
Snow tires definitely improve your AWD’s capabilities in the snow by allowing more traction in slippery snow and icy conditions. Most modern AWD vehicles have sophisticated electronic traction aids that assist the vehicle to stay on track when driving on low traction surfaces such as snow, mud, and ice.
Real-world testing has proven that snow tires greatly improves the vehicles stopping abilities, obstacle avoidance, snowy hill-start, traction as well as acceleration and breaking.
When testing winter tire traction and breaking the vehicle is driven up to 50MPH and then stopped immediately. The test was done between two identical vehicles. One was an AWD and the other a 2WD.
Results showed the 2WD vehicle with snow tires accelerated much quicker and reached 50 Km/h way quicker than the AWD with standard tires. The stopping distance of was over 33 meters shorter with the snow tires.
Hill climbing in snow
The AWD with standard tires only made a few short meters up the hill and then proceeded to slide backward. The 2WD with snow tires managed it all the way up the snowy hill without much loss of traction.
Snow Hill Braking
The snow braking test was done on a 10 % decline. They attempted to stop mid-way down the hill.
AWD slid all the way down the hill with little to no control or traction. The 2WD managed to stop after a few meters.
Both the test vehicles were driven at 45km/hour and attempted to avoid an obstacle. The 2WD avoided the obstacle by performing an emergency avoidance man-oeuvre and succeeded. The AWD drove at 10km/h slower with all the traction control and other stability aids activated and still collided with the obstacle. The AWD back-end stepped out with major under-steer in the front and become very hard to control and unsafe.
The above real-world testing found the winter tires to be much more effective on snow vs the AWD with regular tires. It passed all the test and out-performed the AWD in every department.
Do You Really Need An AWD For Snow And Ice Driving?
Almost half of all road accidents in the US alone are due to low traction surfaces like snow and ice caused by inclement weather. Over 2000 people die every year as a result of road accidents on slippery roads. This is enough for car manufacturers to punt AWD as the solution to safer snow and ice driving in winter. But is this accurate and the most cost-effective solution for winter driving?
Many people become overconfident and are of the perception that an AWD allows them to drive as fast or even faster on snow-filled roads. Many are surprised when the vehicle veers off course and into an embankment. What they didn’t realize was that an AWD is not about steering and stopping in snow driving conditions. The rules of physics still apply to AWD’s and you should never rely 100% on your vehicle as they have limitations. An all-wheel-drive by itself is not enough to stop a vehicle heading speeding toward a sharp bend on a snowy night. Many tests prove that winter tires improve handling, cornering and stopping much better than an AWD with all-season tires in a variety of driving situations.
So this proves that investing in a good set of winter tires is a much cheaper alternative than a several-thousand-dollar premium you’ll pay for an all-wheel-drive vehicle.
Whatever configuration your vehicle is 2WD/4WD/AWD the fact remains there is no getting around the laws of physics.
AWD and 4WD will allow you to drive slightly faster on slippery surfaces but even a heavily modified vehicle can lose traction and spin out of control if driven recklessly or irresponsibly. Always practice responsible driving techniques by maintaining a safe following distance between yourself and the vehicle ahead of you. Increase the distance on slippery snow roads as tires and brakes are less effective under low traction and your stopping distance is increased on slippery surfaces. Always scan the road ahead and pay attention to changes in the road surface for frozen ice patches and water collections.
Remember, if you reside in a part of the world that gets heavy snow frequently throughout the year or for the majority of your winter season, always ensure that whatever vehicle you drive, suitable snow or winter tires are fitted. AWD or 4WD alone is not enough. Your vehicles electronic traction systems function much better with the correct tires and you have more of a safety advantage with the correct tires, preferably an AWD and safe driving practice.
Happy 4 Wheeling and remember, Safety First!!!