How they differ, which is better, and which you should buy?
There's no difference between 4WD vs AWD, right? Wrong. With the rise of the crossover over the last two decades, the line between a softroader and a genuine off-roader has become blurred, and with it, so has the line between cars with all-wheel drive and vehicles with 4-wheel drive. Many feel these terms can be used interchangeably, but the truth is, while similar, these two acronyms represent very different drivetrains. While previously, these systems were the reserve of off-road machines and campers with 4WD, nowadays you can have four driven wheels on everything from a Toyota Camry or Dodge Charger to Mazda 3, or a Toyota Prius, awd carsand even on a minivan like the Toyota Sienna, or a van like the Ford Transit. But what is the difference between AWD cars and 4WD vehicles? How do these systems work? And importantly, which one is best for your needs?
AWD and 4WD are similar, but ultimately different, concepts. The former is an abbreviation of all-wheel drive while the latter refers similarly to four-wheel drive. While both work on the premise of drive being sent to both the front and rear axle of a vehicle, they differ in their practical uses. The list of 4-wheel-drive cars is much shorter than all-wheel-drive vehicles because 4WD is the reserve of trucks and off-roaders, whereas as you can get AWD sports cars, AWD sedans, and even a number of hybrid AWD machines. These primarily focus on regular on-road driving while traditionally, 4WD is off-road oriented.
The variations used to be easy to discern, as the meaning of AWD was simple - power reached all four corners all the time, enabling supreme traction in wet and slippery conditions. This meant AWD vehicles could handle rain and snow with remarkable ease, in moderation. 4WD could be had as both full- and part-time, most commonly relying on rear-wheel drive until you got into a sticky situation, when you could then engage and power the front wheels of your 4WD machine. 4WD cars are purer in their purpose, which is also why they have a low-range transfer case for maximized torque delivery, while AWD is a more watered down system for common use. Nowadays, however, all-wheel-drive systems are more complex than ever before, and some operate on a part-time basis, which we'll get to in a moment. Other differentiating factors are that AWD uses differentials and clutch packs to allow the axles to operate at different speeds, whereas 4WD locks the axles in unison - great for digging you out of a rut, but not so great for handling.
As technology progresses, so too do AWD systems. Now, there are two primary classifications: full-time and part-time:
As with most mechanical systems, there are certain pros and cons to having an all-wheel drive car:
While AWD has advanced substantially over the decades, 4WD, or 4x4 as it's alternatively known, has remained fairly unaltered since the early days of its use. Like AWD, both permanent and non-permanent solutions exist, but whichever is used, the focus is on off-road capability, and to this end, a low-range transfer case is a must-have item in order for a vehicle to be classified as 4WD. This drivetrain also locks the front and rear driveshafts together, which hinders the ability to make tight turns as the wheels can't rotate at independent speeds.
We receive countless emails asking the same question: "4-wheel drive vs all-wheel drive - which is better?" The answer to that is very dependant on your needs, and particularly your environment. For example, when it comes to 4WD vs AWD in snow, both afford advantages over two-wheel-drive equivalents, but 4WD is better for deeper snowdrifts and roads that haven't had the benefit of a fresh snowplow. However, in general, for light snow, all-wheel drive is highly adept.
The genuine need for 4WD comes when you spend most of your time outdoors, climbing rocks, going deep into the unknown, or even when simply towing in tricky conditions. These vehicles suffer on-road but come into their own when you head off the beaten path. If this is your lifestyle, 4WD will get you where you want to go.
Outside of inclement weather benefits, you need to look at what you'll use a vehicle for. If most of your time is spent on the tarmac with the odd excursion down a light gravel trail, an AWD SUV with a little extra ride height is more than capable, meaning, for most, all-wheel drive will be sufficient.
Both these drivetrains are adept at handling snow and ice, maximizing available traction purely by virtue of extra torque distribution. However, snow tires or snow chains have just as much of an effect as the number of driven wheels you have. For road use in urban areas, AWD will suffice, but in areas with heavy snowfall and infrequent grading and plowing of these roads, 4WD vehicles will always give you the advantage.
While these two concepts seem at odds with one another, the advent of modern computer systems actually makes this possible. A number of off-roaders give users the option to select either 2H or 4H manually, but 4AUTO modes allow the systems to engage and disengage axles automatically depending on the surface you're driving on. Land Rover's Terrain Response 2 program is one such example.
AWD and 4WD are different types of powertrains that both drive all four wheels. 4WD and 4x4, however, are two names for the same concept, suited more to off-roading than anything else.
Technically, yes, AWD SUVs can go off-road, and some are even relatively capable. The Honda Passport, for example, has enough ground clearance and a short enough wheelbase to traverse most obstacles. A lack of all-terrain rubber and a low-range transfer case, however, means these will never be as capable as their 4x4 counterparts.