AWD v FWD v RWD
Traction
When it comes to buying your new vehicle, should it be FWD (Front Wheel Drive), RWD (Rear Wheel Drive) or AWD (All Wheel Drive)? How the car gets shoved along might not matter to many drivers, however there are some differences between the driving layouts that are worth pointing out. There are some changes occurring where car manufacturers are adopting a new layout for certain key reasons, and we’ll see why shortly. What type of drive system you prefer really depends on what kind of a driver you are and the conditions you usually find yourself drive in.
Let’s take a look at the three types for drive trains and note the differences.
Firstly we’ll start with RWD, mainly because this can be lots of fun to drive. A RWD car has a simple design where the drive shaft runs the length of the vehicle: from the engine to the rear wheels. The design is generally simple and rugged. It’s less likely to break when running over a curb or large pothole. FWD vehicles are more complex, and with the added weight over the front axle the chances you’re going to break something in the FWD design is more likely. FWD set-ups incorporate half-shafts and constant velocity (CV) joints that are more susceptible to damage than a RWD car’s solid axle.
RWD cars usually have a slightly better weight distribution (not as heavy at the front end compared with a FWD car), creating better handling because of this. A RWD car spreads the weight of its drivetrain more evenly front-to-rear. But an issue with the RWD layout can arise when the road conditions get slippery. Rain, snow and ice create scenarios where loss of traction at the rear becomes more likely in a RWD car.
FWD cars do, however, provide better economy – not only in fuel consumption but also in manufacturing costs. With fewer parts the drivetrain is easier and cheaper to mount into the car as it progresses down the assembly line. FWD cars are often lighter than RWD equivalents thanks to the design not having to use separate transmission and axle assemblies used in a RWD car. Reduction in weight leads to better fuel economy on the road, and this is a big draw card for new car buyers.
In certain conditions FWD offers better traction compared with a RWD car. In the rain and snow, FWD gets better traction on the driving wheels because the front wheels have the extra engine and transaxle weight sitting on top of the front driving wheels – which helps to get better grip in slippery conditions. Also, the front wheels are pulling rather than pushing the car along, aiding steering control in poor road conditions.
Being nose heavy, FWD cars aren’t usually quite as nimble and fast through the corners as RWD cars. When road conditions allow for higher speeds to be attained, FWD cars have to steer and drive the car with extra weight at the front. This is why very few “serious” performance cars are FWD. Maintenance costs are higher compared with RWD, so new bits like CV joints and boots will need to be replaced as the kilometres pass by.
This leaves us with AWD, and the best thing about AWD is that it gives some of the advantages of both RWD and FWD. The number one advantage of AWD is excellent traction in dry and wet road conditions. Some AWD designs lean slightly toward the front wheels doing more work, while others lean more toward the rear wheels doing more of the work. The RWD-based versions are usually more performance-oriented but any of the AWD cars will do a top job of balancing the car’s handling and driving dynamics.
AWD cars do cost more to buy compared with RWD and FWD cousins. This is because they cost more to produce with all the extra drive train components. The extra running gear also costs more to maintain. AWD systems are also heavier drive systems which makes for higher fuel consumption. The higher fuel consumption, higher production costs and higher maintenance costs will put some buyers off, however a die-hard Subaru fan will have you think otherwise. For ultimate performance, the AWD system can’t be beaten.
There are electronic traction control systems and driver aids that are getting better-and-better which do aid both the car’s handling and performance characteristics, as well as safety. And, particularly in variable road conditions that might be wet and slippery, these extra electronic control systems can’t be beat. These systems are widely used in many FWD, RWD and AWD cars.
The trend is that new car buyers are looking for more SUV and all-purpose vehicles to buy. It has become simpler for automakers to reconfigure FWD models into AWD formulas where the AWD system is front-wheel power biased. We are seeing more of these vehicle types on our road, which also means there is a decline in new RWD cars being bought.
Just for interest sake: Holden are still keeping the Commodore name, however the new Commodore won’t have a rear-wheel drive variant. Instead, it’ll be offered in a front-wheel drive configuration for mainstream models, while a naturally aspirated 3.6-litre V6 AWD model will be the performance model in the line-up. With a nine-speed automatic gearbox, no differential with dual-clutch control systems controlling front and rear wheels independently, and torque vectoring the AWD model will be a performer.
Holden Commodore AWD
Also interesting is that BMW Motorsport engineers are looking to produce M-badged cars with an AWD model as well as a RWD variant. With BMW’s M cars getting so powerful, the boss of BMW’s M Division, Frank van Meel, said that it’s getting hard to sell M cars without AWD in markets like Canada and Switzerland where conditions are slippery.
BMW M5 AWD
There is only so much horsepower you can put through two wheels before obtaining the grip needed to accelerate fast is compromised. Even with the best traction and launch control aids, 2WD systems are beaten by AWD systems, and when engines have such immense power now, AWD is the only logical step forward for performance car manufacturers like BMW. Audi, Porsche and Nissan already have plenty of experience with AWD performance models.
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