As a general rule, 4×4 traction (or 4WD) can be found on large SUV vehicles, such as the Nissan Patrol. Of course, nowadays with so much technology, you will find several versions of 4WD, but the basic principles are the same.
Compared with the integral traction (AWD), the 4WD system can be switched off if fuel economy is required . From a mechanical point of view, the 4WD drivetrain uses two differential and a transfer box, while AWD transmission uses three differentials (one in front, one center and one in the back).
In the case of the first type of traction this transfers power from the engine to an invention called the transfer box. This splits the power equally between the two axes: one in front and one in back. In this way, the car enjoys equal power to all four wheels. It sounds good and can be more than useful in case of rough roads, but has a big disadvantage. You do not need full power in most road conditions, for example when traveling on a straight and dry road with 55 km / h. For this reason, the car’s fuel consumption increases rapidly.
Fortunately, these systems can overcome the problem. With a handle, you can transfer the power to the driving wheels, used in ordinary situations. There are newer models that use a button for this “transformation” or just employ the sensors feeding the car’s electronic brain to decides when it activates 4×4 and when not to.
Now, the most notable difference of 4WD systems and AWD is that the latter works all the time, and cannot be stopped, so you will feel it at the gas pump. Moreover, this AWD variant is not appropriate in all situations, even in rough terrain. The positive side of such traction consists of a better grip and control in most driving situations, but more accurate maneuverability and traction in tight turns.
AWD traction comes in two forms: mechanically or electronically controlled. Compared with 4WD, the AWD traction changes constantly the transmitted power from the front to the rear, depending on the encountered conditions. Moreover, such traction may even alternate power between wheels on the same axle, whether it’s the front or the rear one. This last feature is called torque vector system.
The AWD traction is especially suitable in wet conditions, so no wonder that models like the Subaru Impreza WRX STI, Mitsubishi Lancer EVO X, Mercedes-Benz E63 AMG S, Audi R8 or Lamborghini HURACAN are equipped with such systems. Let’s not forget that the “daddy” of four-wheel drive, the legendary Audi Quattro, dominated the motorsport world for nearly a decade helped by such a system.