YOU finally decided to buy an SUV. You’ve chosen the model, the engine size and even the color but there’s one consideration you have to make: to choose between 2 wheel drive (2WD) or 4 wheel drive (4WD) version.
Your needs matter
A lot of people will buy SUV but will never take it off road. If the first consideration is to just fetch the kids from school, take long highway trips and sit comfortably and high, then 2WD version may be just fine. Two wheel drive means only two wheels are powered. The other two wheels are just along for the drive.
If you choose to buy 2WD SUV, make sure that the manufacturer offers a the option of a limited slip differential. The system allows power to be transferred to either rear wheel. This version can handle dirt roads and gravel washes completely. There are also SUVs with 2WD power that is delivered via the front wheels. This offers superior traction during the rainy season.
There are two types of 2WD: front wheel drive and rear wheel drive.
Four wheel drive means all four wheels are powered. If you choose 4WD, you will have numerous variations from which to choose. One of the most commonly used 4WD systems employs a simple high/low transfer case which routes power equally to the front and rear differentials.
There are two main types of 4WD: AWD and old fashioned 4WD.
When engaged, both front and rear wheels turn at the same rate of speed. This system is called part-time 4WD and is intended only for use off road. Because a vehicle’s wheels rotate at different speeds when turning a corner, part- time 4WD cannot be engaged on dry pavement or at speeds greater than 40 mph.
A clever twist on part-time 4WD is called on-demand 4WD. The system operates in the 2WD mode but will automatically divert power to the other wheels if slippage is detected, thus temporarily engaging the 4WD until traction is regained. This system can be left on during normal driving conditions.
Next up is the full-time 4WD system. Full-time 4WD employs front, rear and center differentials that allow individual wheel speed to vary. SUVs so equipped can operate in the 4WD mode at all times and on any surface condition. When disengaged, full-time 4WD operates as normal 2WD. This system best serves those who occasionally require 4WD under normal driving situations.
Manufacturers use many different names for their 4WD systems. To be sure you are looking at full-time 4WD, the transfer case must be equipped with some form of a center differential.
Finally we come to all-wheel drive (AWD). All-wheel drive means the system is permanently engaged at all times. Power is sent to any or all wheels, controlled by a series of electronic gears that detect wheel slippage.
The advantage of 4WD is better traction in all conditions.