A 4x4 is any vehicle that utilizes four-wheel drive, which means that power goes to all of the wheels to create motion instead of just the pair at the front or rear. Many types of vehicle can be equipped with four-wheel drive, but the term 4x4 usually evokes the image of a truck or a sport utility vehicle. Having four-wheel drive is useful in many situations, such as snowy roads or driving in off-road conditions, since it provides a significant amount of additional traction. Some of the drawbacks of four-wheel drive include the purchase price and lack of fuel efficiency.
Most vehicles only send power to two wheels, which is called two-wheel drive. The car is either pulled by the front wheels, called front-wheel drive, or pushed by the ones in the back, which is referred to as rear-wheel drive. On a 4x4, all of the wheels receive power from the engine to propel the vehicle in the desired direction.
Many types of vehicles come available equipped with four-wheel drive. Examples include cars, trucks, sport utility vehicles, and all-terrain vehicles (ATVs) which are designed specifically for off-road recreational usage. Usually when the term 4x4 is used, it brings to mind a truck or sport utility vehicle. These vehicles have enjoyed extensive popularity for many years, but ever increasing fuel prices are making them less desirable than more efficient models.
An important reason for the popularity of the 4x4 is the increased traction that is possible when using a four-wheel drive system. When operating with two- wheel drive, the car is unable to move if the drive wheels slip. Since all of the wheels on a 4x4 have power, it is much less likely to get stuck; if one wheel slips, the others are able to safely propel the vehicle. This traction is quite useful when dealing with slippery, icy, or snowy road conditions or when using the vehicle to drive off-road. Many people feel safer with the added traction, and some say four-wheel drive can improve handling of the vehicle in normal situations as well.
In spite of the benefits, there are also a few drawbacks to owning a 4x4. One of these is the increased expense to purchase one; when comparing equivalent vehicles, a model with four-wheel drive usually has a significantly higher price. It is also slightly more costly to repair if problems occur with the drive train due to the additional complexity of the four-wheel drive system. Finally, vehicles with four-wheel drive usually are less fuel efficient than their counterparts.