Mercedes Vs Toyota

AWD vs 4WD

Right, so I am chilling in my house and then my friend calls me and she is like, Ace, I am having an argument with my friends over the difference between 4WD and AWD. I wasn't ready but I feel the response I gave her was sufficient. (Spoiler alert, this will be more informative than entertaining but like always, I will try to keep you interested long enough to see it thru).

I did some research and I realised manufacturers are in the habit of throwing these terms around, mostly for marketing purposes. So they will slap a 4WD sticker on a car to appeal to a specific target market.

Before we dive deep into this article, let us clarify some basics first. Different manufacturers go about the business of delivering power to the wheels from the engine differently. In this specific article, I will focus on power delivered to all wheels. I will, however, break this article into two parts and start with AWD systems.

This printscreen shows the symmetry... 
To try to break this article down, let us use the most common AWD system around as the example, Subaru's Symmetrical AWD. The new term, Symmetrical, simply refers to the power delivery layout in Subaru cars. It starts from a Boxer engine which lies dead centre, from there power goes to the transmission, front wheels then straight to the back wheels. PERFECTLY BALANCED (as all things should be). Here is the first notable point, power is always transmitted to all four wheels, although with a slight bias to the front wheels, to help improve fuel consumption. Most Subaru cars have a power split of around 60-40, with the front getting more power. This can be varied to a 50-50 power split depending on the road conditions.

From the Subaru example, we now have an idea of how AWD systems work. Power can be delivered to all wheels, the only difference is how manufacturers implement this.

DISCLAIMER; Although Subaru will call their cars Symmetrical AWD, the systems in place vary from car to car.
For Instance, Subarus inclined towards Racing and Rallying and Peak performances (WRX and WRX STi) will adopt a different approach. I'd love to get into the details on those but this article has already achieved its intended purpose.

Something else worth noting is that these cars use open differentials, (this means that power will only go to the wheel with the least amount of resistance, so if one wheel is off the ground, it will basically just spin and you are probably stuck ). Open Diffs were a problem in the past and Subaru has sorted out this by introducing a system called VDC (Vehicle Dynamic Control). What this does is power redistribution. Immediately the car detects a wheel is slipping (no traction), the system brakes the individual wheel, then power is redistributed to the wheels on the ground. (Pretty impressive huh).  Differentials are pretty key when it comes to all-wheel-drive cars so I will definitely talk about it on the 4WD system.

AWD systems vary from one car to another, this time we focused on the one Subaru adopts. Nissan has theirs and so do Audi just to name a few. Regular AWD cars will normally use either front wheels or rear wheels most of the time and only employ the other set when needed. (The main differentiating factor is that the other set will be powered automatically by the car once it notices there is no traction).

Find you a car that has a way of sorting out the open diff issue, else, your all-wheel-drive system will not be as effective.

I will however insist, these terms are loosely used, and the difference isn't as obvious as we'de want it to be. Focus on one car, then check the technology it employs, if it fits your needs then you can go for it... the market has everything for everyone...



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