You’ve heard of 4-wheel drive (4WD) and all-wheel drive (AWD), but if a car only has 4 wheels anyway... what’s the difference? And what’s the big deal, really?

Increasingly, these are becoming becoming popular options for car buyers and so a little knowledge could go a long way in helping you make an informed decision next time you hit the local dealership. All SUVs and pickup trucks offer 4WD systems, and even some minivans like the Toyota Sienna and Pontiac Montana, offer available AWD systems. Oftentimes, more than one system is available for any given vehicle, leaving consumers puzzled.

With so many options to choose from, it’s easy for drivers to get confused by a barrage of acronyms, each more meaningless than the last. For most consumers, there are three basic options: Part-time 4WD, full-time 4WD, or all-wheel drive.

Although each system has its own merits, one thing is certain-with 4WD you are less likely to get stuck in snow or mud. On the other hand, any 4WD system will make your vehicle less fuel efficient and more complicated to repair and maintain. Most consumers want 4WD because it adds a measure of security to a vehicle, but finding out and deciding which system is right for you is both an important and complex job.

Part-time 4WD
This most basic system provides a choice of settings that can be changed depending on your driving situation. In this setting, each of the four wheels constantly gets 25% of the torque to prevent wheelspin. In newer models, the driver can shift from 2WD to 4WD while driving. One drawback of part-time 4WD is that it must be continually engaged and then disengaged in conditions of light rain or snow. This type of system is best for people who really don’t need 4WD, but occasionally go off-roading and want a little extra security when it snows.

Full-time 4WD
Unlike part-time 4WD, full-time 4WD, is just that-a system that can continually remain operating. This more advanced, convenient form of 4WD allows you to remain engaged while on dry pavement. Full-time 4WD is best for people who regularly drive in slippery conditions where constant shifting between 2WD and 4WD can become tedious.

All-Wheel Drive
All-wheel drive is similar to full-time 4WD in that the system is always sending power to the wheels with the most traction, but AWD has no 2WD switch. It is always operating in 4WD mode. When the road gets slippery, the AWD system locks the axles and automatically distributes power to all four of the tires. In many cases, AWD vehicles have no on/off switch. Some AWD systems are more rugged than others, though most can’t be taken into extreme off-road situations. AWD systems work well in cars and crossover vehicles because they don’t add much weight and make them true all-weather vehicles.

A Reasonable Alternative
For most consumers, a set of quality all-season tires is a much better and less-expensive alternative to pricey and complex all-wheel-drive systems. Even the most advanced 4WD vehicle will be left spinning its wheels in the snow if they are using touring tires. Take a look at what kind of driving you normally do. Once you determine what type of vehicle best suits your needs, you can assess what type of system you need to get the job done. In some cases it may simply be 2WD with snow tires. In others, you may want to consider a more "robust" 4WD system with a low-range option.

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