4WD, AWD and 4x4, Full Time or Part Time?

OK guys, what is the difference between 4WD, AWD and 4x4? Why is it has full time and part time 4WD? Which one is better? First, word of caution; manufacturers tend to obscure the true nature of their 4WD/AWD systems behind fantasy names like "Active 4WD", "Quadra-Drive", etc. - others might call their automatic AWD "Real Time 4WD".

There are so many different 4WD systems on the market now that it is important to be precise and specific. It is important to call AWD when it is AWD and full time 4WD when it is full time 4WD. Just to say 4x4 is not sufficient any longer.

Part time 4WD is a system that can only be used part of the time in four wheel drive (Harald Pietschmann, 1997). This 4WD system was created to provide a vehicle with more traction to either carry higher loads and/or to travel in adverse terrain conditions. It can only be used for adverse terrain conditions - not for dry pavement. Typical lever settings are 2WD, 4WD Hi, 4WD Lo.

Image shows link in transfer case open. Car is in 2WD.


Very good off-road. Most competent when combined with axle differential locks.
• 2WD setting must be used on dry pavement.
• If 4WD is selected, all 4 wheels are permanently powered.
Prominent examples: 1942 Willys, Jeep Wrangler.

Link is now closed. Both drive shafts are linked solidly. Car is in 4WD.


1 = engine
2 = transfer case
3 = rear drive shaft
4 = front drive shaft
5 = front differential
6 = rear differential
7 = rear axle
8 = front axle.



Full time 4WD - also called permanent 4WD, can be used full time on all surfaces including pavement. Full time 4WD was created to provide a vehicle with more traction and to make 4WD more useful for everyday life. The additional feature of a differential incorporated into the transfer case makes it possible to use 4WD all the time. 2WD is no longer available. Can still be a strong workhorse. Some rough terrain competence is retained - the priority is added stability as a safety gain for everyday driving.

Full time 4WD layout.



A = center differential
B = front axle differential
C = rear axle differential






Typical lever or switch settings are 4WD Hi, 4WD Lo. Very good off-road when center diff is lockable. Even better when combined with axle differential locks.
• All 4 wheels are permanently powered.
Prominent examples: pre 2006 Mercedes M-Class, Mercedes G500, LandRover, RangeRover, Toyota Prado.