2WD VS AWD-Which One Is Better?

In years past, I have always preferred 2WD over AWD. The older cars with naturally aspirated engines didn’t make anywhere near as much torque (or horsepower) as a modern turbocharged engine. So a 2WD platform could easily handle the power.  Additionally, 2wd cars were lighter with a better weight balance. This improved the vehicle dynamics in the center of the corner.

Benefits of a Modern Turbocharged Engine

Modern turbocharged engines produce a surplus of torque and generally a large quantity of it in the middle of the power band.  Usually, it is so much torque, that the rear tires struggle to keep traction when you accelerate hard. They make so much torque that they will spin the tires in the first two gears in perfect conditions when accelerating in a straight line and after wider, more sticky rear tires have been added.  

AWD Drivetrain

Considering the modern AWD drivetrain, computer-controlled systems with information from the stability control software, steering angle, throttle, and yaw sensors can change the balance of the car in different parts of a corner.  Thus attempting to level the playing field of the mid-corner handling with respect to a 2WD platform.  The AWD components are getting lighter and lighter, so the weight penalty is diminishing as well.  What little penalty you have with the larger mass/weight, is more than made up for by the extra acceleration ability provided by the additional traction.

Examples of 2WD vs. AWD

911 Turbo S

The new 911 turbo S is a perfect example of the modern AWD intelligence.  The vehicle shifts engine torque to the front wheels on deceleration, to reduce the rear engine car’s tendency to oversteer or overrotate on corner entry. 

In the center of the corner, it shifts the engine torque back to the rear wheels. So the car will understeer less in the middle of the corner or max direction change. Then, it adds torque to the front wheels in proportion to how much power you request or wheel slip you create. So the car increases in its stability under hard acceleration leaving the corner.

F90 M5

The new F90 M5 shifts engine torque on deceleration to the rear wheels to reduce the front engine car’s tendency to understeer on corner entry.  (This difference to the 911 is due to the weight proportion of the vehicle, or where the heaviest part of the car resides.)  

Then in the center of the corner, the F90 M5 shifts the engine torque slightly to the front wheels. So the car has a predictable amount of understeer in the middle of the corner. Finally, it adds torque to the front wheels in proportion to how much power you request or wheel slip you create. So the car increases stability under hard acceleration, keeping the car in line.

Modern computer-controlled AWD is amazing and I don’t think I want to own a car without it ever again!

Why are Racing cars 2WD?

The governing bodies have made it illegal to have an AWD car in road racing as of the last decade and a half. This was done years ago so that the 2WD cars would not have a performance disadvantage when racing against AWD cars, particularly in standing start formats. 

I understand the rationale, but it’s a shame because AWD has advantages that would’ve accelerated the manufacturer development curve in motorsport, thereby making better AWD road cars for all. Considering the shift toward AWD performance road cars, this could change in the future.