AWD Should Be an Industry Standard
Having too many options makes a decision overly complicated. All Wheel Drive (AWD, Four Wheel Drive (4WD), symmetrical, asymmetrical, full-time, part-time, Real-Time, how is one supposed to know which is right for them? It’s simple really. Which provides the best traction? All this confusion is intentional. Advertising unique drivetrains while providing limited information is a way for certain companies to market an inferior product in a competitive marketplace. Lets lift the shroud on this automotive mystery.
4WD is a part-time system. A vehicle equipped with standard 4WD will be 2WD until the system is engaged. When engaged both drive shafts and all four wheels spin together. Wheel speed is controlled by the differential, which allows one wheel to slow while the other moves faster. This is necessary for turns, since the inner wheel will follow a tighter line than the outer wheel. Without the differential, the vehicle would bounce out of control while turning. There is a common misconception that 4WD vehicles are the best in severe weather, on pavement. 4WD is best suited for off-road or harsh road use at slow speeds. Ranch trucks, utility vehicles, recreational vehicles all would benefit greatly from a part-time 4WD system.
For on-road use, symmetrical AWD provides the best traction. AWD refers to the full-time nature of the vehicle’s drivetrain. When looked at from above, the drivetrain is the same on one side of the engine as the other, which provides better balance, hence the term symmetrical. AWD will improve vehicle traction even on dry pavement. Lamborghini and Porsche did not put AWD systems in their vehicles because they thought the end user would be taking them off-road or through snowstorms. AWD improves traction by working in tandem with a computer that adjusts torque, power, and resistance in all the wheels, many hundred times a second. With all wheels perfectly tuned to the right output of power the vehicle will stay as in control as the situation allows. This is a driving advantage on any surface. When sitting behind the wheel of a car with a high-end AWD system you will be surprised at the uncanny ability to steer while sliding. It is counterintuitive to be so in control while out of control. You may even have some fun.
Asymmetrical AWD systems can throw themselves out of control through torque Steering. When there is no traction between the wheels and the pavement, the lopsided weight of the asymmetrical system causes the front of the vehicle to move from side to side. This is torque steer. Torque steer can be a problem under all driving conditions. This is why BMW brags a perfect 50/50 weight distribution. It is the ideal platform for handling performance.
Last and most certainly least is 2WD. There are two varieties of 2WD, Front-Wheel-Drive, and Rear-Wheel-Drive. For the average driver I believe 2WD to be a relic. I cannot think of a single situation where I would rather have 2WD than AWD. Because of this and the fact that cars with incredible AWD systems are being sold at competitive prices (Subaru Impreza MSRP $17,495), I will never own or recommend a 2WD car.