All-Wheel Drive – Is This Option Best for You?

The past few years have seen an explosion in the number of vehicles offered with all-wheel drive. From crossovers and SUVs to compact cars and sedans, AWD is becoming almost a “must have” feature for those who live in snowy or inclement weather locales. It is even becoming popular for those that don’t live in these areas. It sounds like a great option – the best of both worlds, right?  Well, that may or may not be true for you.  Understanding the pros and cons of the different drive options and comparing them to your driving conditions will help you make a purchase decision that best meets your needs.

Drive Types

• FWD.  Most of today's passenger cars are of the front-wheel-drive variety. This type of system sends the engine's torque solely to the vehicle's front wheels.
• RWD. Rear-wheel drive is commonly found in trucks, truck-based SUVs, full-size vans, performance cars, and luxury sedans, and it sends the engine’s torque to the rear wheels. 
• 4WD.  Four-wheel drive systems are intended for part-time use only. They are designed for driving off-road on gravel/dirt roads or when road conditions are slippery. At all other times, these vehicles must be driven in two-wheel drive. 
• AWD.  All-wheel-drive systems run all the time with no user input, varying the amount of power to each wheel. 

How is AWD different from 4WD?

AWD is often interchanged with four-wheel drive in advertising, which causes many people to think they are the same thing. However, there are several key differences between AWD and 4WD systems.

• Variable individual axle speeds.  AWD systems can vary the power delivered to each axel.  That’s why they are different from four-wheel-drive systems, which by definition, use systems that cannot vary the individual axle speeds. This means you cannot drive four-wheel drive on dry streets and roads, or the axles will bind because your vehicle's inside wheels turn slower than the outside wheels when you go around a corner and the vehicle will buck and hop awkwardly around tight turns.
• Always on?  Traditional four-wheel-drive systems in many vehicles are classified as part-time systems, which means the vehicle operates in rear-wheel drive until the four-wheel drive is selected by the driver. You’ll find part-time four-wheel-drive systems in many trucks and off-road SUVs. However, certain models built by automakers such as Jeep and Land Rover have full-time four-wheel-drive systems that are always on. All-wheel-drive systems apply varying levels of power to each wheel all the time.
• Transfer case vs. center differential.  While AWD and four-wheel-drive systems both have front and rear differentials, four-wheel-drive systems usually feature a transfer case instead of a center differential. This part has a number of gears encased in it that split power to the front and rear axles, providing both sets of wheels with maximum torque.
• High vs. low range gearing.  Transfer cases also usually provide high and low range gearing. The high range will allow you to drive at normal speeds and is typically used for icy conditions or snow-covered roads. Using high range may also make sense on dirt roads, or in light off-road situations. Low range gearing will limit your top speed, but it also provides a lot more power for more intense off-road conditions such as rock climbing, deep sand, steep terrain, or muddy trails.

Pros & Cons of AWD vs. FWD

• Pros
  • Improved traction in slippery conditions.  An AWD vehicle will accelerate on slippery roads significantly better than a vehicle with two-wheel drive. If there's snow, ice, mud, or gravel on the road, it will be more difficult for a two-wheel-drive vehicle's wheels to get good initial traction when accelerating. This could cause the vehicle to lose control, slip, and slide.
  • Less chance of spinning when exiting a corner.  More and more performance vehicles are using AWD for its ability to harness horsepower without spinning the tires.
  • Improved acceleration in poor weather conditions.  Since AWD turns four wheels instead of just two, there's that much more grip when the available traction is low, and you can accelerate better with less or even no tire slippage. The vehicle feels stable and doesn't slip or fishtail in a way that makes your heart race. In almost any slippery situation, an AWD vehicle is able to accelerate from a stop better than one with front-wheel drive or rear-wheel drive with identical tires.
  • Higher resale value.  This is especially true if you live in an area with inclement weather conditions.
• Cons of AWD Vehicles
  • Higher upfront costs.  AWD costs more than its 2WD counterparts.
  • Ownership costs are higher.  AWD vehicles typically use more fuel and additional drivetrain components require maintenance.
  • Less legroom/interior space.  Additional drivetrain components require space which takes away from interior space.
  • False sense of security.  It is easy to be lured by an automaker's advertising and think that having AWD means you can drive in the snow or rain as easily as you would in dry conditions. But the truth is that AWD and four-wheel drive help only with acceleration and traction. Braking distances and handling will be the same as with a two-wheel-drive vehicle.

So what should you choose?

It may not make sense to buy an AWD vehicle if you only occasionally go on off-road outings or ski trips, or if 90 percent of the time you operate the vehicle on paved and well-maintained roads. Choosing a front-wheel-drive vehicle will save money across the board: on the price of the car, in lower fuel costs, and in lower maintenance costs. Choosing a four-wheel-drive vehicle will enable you to decide when you need power at all four wheels, giving you the best performance in the toughest situations. If you frequently drive in harsh conditions, purchasing a vehicle equipped with AWD may be your best bet. Whatever you decide, make sure you take the time to weigh the pros and cons and find the right car for you.