What is the difference between all-wheel-drive (AWD) and front-wheel-drive (FWD)?
The main difference is where the engine's power ends up. In FWD vehicles, the engine powers the front axle, whereas in AWD vehicles, the engine powers both front and rear axles.
Here's a brief rundown on the four types of wheel drive systems:
Front-Wheel Drive: Many new cars on the road today are front-wheel-drive vehicles, including some SUVs and crossovers, even though consumers may assume they're AWD or four-wheel-drive because of their body style. FWD vehicles usually have better fuel economy than AWD models since it's more efficient to power just two wheels.
Since the engine is positioned in the front and pushes down on the front-driven wheels in a front-wheel-drive car -- and basically pulls the weight of the vehicle -- the effect of oversteer (rear end of the vehicle sliding out in cornering and causing a tighter turn than intended) is limited. FWD cars are good at climbing hills and perform well in slippery conditions and light snow. From a manufacturer's standpoint, FWD vehicles are beneficial because they are cheaper to manufacture and use space more efficiently.
Rear-Wheel Drive: Rear-drive systems are usually found in sports cars, pickup trucks, older truck-based SUVs and luxury high-performance sedans. It is a two-wheel drive system that pushes the car from the rear axle. Rear-wheel drive systems (RWD) enable better handling in performance cars by distributing weight more evenly.
In addition, since the front wheels aren't in charge of both steering and powering the vehicle, makers of rear-wheel-drive cars are free to tune the suspension system for handling superiority. These days, most performance RWD cars typically have AWD options available as well. RWD trucks are made with powerful and heavy parts that provide better traction when hauling a heavy load. RWD vehicles have inferior traction control when road conditions are slippery, however.
All-Wheel Drive: AWD systems deliver power to each corner of the vehicle, similar to 4WD cars. However, unlike 4WD cars, AWD is always engaged, and delivers varying amounts of power to the axles depending on traction conditions. All-wheel-drive systems primarily power one set of axles, either front or rear. When the car feels traction loss in one axle, it will automatically divert more power to the other axle to compensate.
Not all AWD systems utilize the same power ratio. For example, Subaru's all-wheel-drive system continuously sends at least 20% of the engine's power output to the rear axle, with the possibility of directing more if necessary. Other systems exclusively power the front axle and only rebalance engine output to the rear when the front tires are losing traction.
AWD cars work well in moderate off-road driving situations, or when driving conditions are prone to change due to terrain variation or volatile weather conditions. In addition, AWD vehicles provide great overall traction during acceleration due to all four wheels being engaged. AWD systems are commonly found in crossovers SUVs, and minivans, but also commonly make an appearance as an option for some rear-wheel-drive cars.
Four-Wheel Drive: Four-wheel-drive (4WD) vehicles generally have a more off-road-oriented heritage and can handle off-road use like traversing over snow or water, scaling rocky terrain, or climbing steep hills with poor surface traction.
When enabled, four-wheel-drive systems send power to all four wheels using front and rear differentials plus a transfer case that distributes power equally regardless of traction. In addition, some 4WD systems have two gear ranges, high and low. The low gear range proves especially helpful when low-speed climbing power is required.
There are three different versions of modern four-wheel-drive vehicles. Full-time systems are always engaged, automatic systems switch between 2WD and 4WD automatically, and part-time systems require the driver to manually switch their 4WD vehicle between two-wheel drive and four-wheel-drive modes.
Is an All-Wheel-Drive or Four-Wheel-Drive Vehicle Worth It?
It depends on the driving conditions you plan to encounter. Two-wheel-drive cars handle rain and light snowfall just fine, with front-wheel drive cars generally eking out rear-wheel cars in safety. Rear-wheel-drive cars excel when performance is key (although all-wheel-drive systems can provide more traction). All-wheel drive vehicles are great for light off-road driving and typical snow conditions. If you're powering through heavy snow or tackling extreme off-road terrain, a four-wheel-drive vehicle with high ground clearance and a low gear range is the set of wheels you should be looking for.
In addition to weather and terrain conditions, fuel efficiency is another factor that should be considered. Both four-wheel-drive and all-wheel-drive systems contribute substantial heft to the vehicle, so you end up trading efficient fuel economy for that extra traction.
Traversing Winter Terrain
Safety and handling is another concern. Many potential car buyers view all-wheel-drive and four-wheel-drive as safer due to the increased traction they provide. However, that better traction isn't the same thing as safer turning or braking, especially when ice is a factor. Sure, the extra traction is nice when you need to get going, but stopping is another story.
Four-wheel-drive and all-wheel-drive vehicles are actually involved in more icy condition-related accidents than their lighter two-wheel-drive counterparts, and their drivers' misconceptions about the limitations of their 4WD and AWD drivetrains often plays a part. Even on dry streets, heavier four-wheel-drive and all-wheel drive vehicles require more distance to come to a complete stop.
Good Tires Are Essential
Another important thing to remember is that when you're driving in winter weather, a good set of winter tires is essential. Numerous independent studies have shown that good tires play the largest part in determining a vehicle's safety performance when driving through snow and ice. That is because snow tires are made from a softer kind of rubber than standard tires. Their more pliable texture enables superior traction when the temperature drops.
In addition, winter tires feature specialized treads that are designed to carve into snow and eject it out of the way. Snow tires are embossed with a three-peak mountain and snowflake logo, so it's easy to see if the tire you're looking at passes snow performance standards and is rated for winter driving.
For many drivers, a two-wheel-drive vehicle is often all that's needed. Throw a set of winter tires on when going through light snowfall and it will perform fine. This is the cheapest option, since all-wheel-drive vehicles are more expensive at the dealership, and they're less fuel efficient, leading to greater fuel costs during your ownership.
A front-wheel-drive vehicle is more versatile and less prone to oversteer. If you live in a warm, dry climate and are a performance enthusiast, a rear-wheel-drive car might be right for you.
But if you're often driving in inclement weather every winter, and AWD or 4WD vehicle is a smart bet. All-wheel-drive cars are jack of all trades. All-wheel-drive cars also redistribute power automatically, so you don't have to worry about fumbling with controls and can just focus on the road.
And if you're actually headed off-road or often find yourself on unplowed roads, a four-wheel-drive vehicle with a low gear range and high clearance provides the best mobility.