by Jim Kerr
The controversy has gone on for decades: which is better – front wheel drive or rear wheel drive? We used to have predominately rear wheel drive (RWD) automobiles on the road, but by the late 1970’s, front wheel drive (FWD) vehicles were beginning to dominate. While the majority of current passenger cars are still front wheel drive, rear wheel drive vehicles are becoming more common. For example, Infiniti has gone back to RWD on their G35 model, and Cadillac has RWD on their new CTS model. So what are the advantages and disadvantages of each drive system?
Let’s look at front wheel drive first, as it is most common. Reduced cost: that is often the reason manufacturers design and build the way they do. FWD systems are cheaper to manufacture and install than RWD systems. There is no driveshaft or rear axle housing to build. The transmission and differential are located in one housing and less parts are needed. It also makes it easier for the designers to locate other parts beneath the vehicle, such as brake lines, fuel lines, and exhaust system.
Reduced weight is another advantage. Lowering a vehicle’s weight improves acceleration, braking, and fuel economy. Traction is improved by having the weight of the engine and transaxle over the drive wheels. This is a big advantage on slippery roads.
A big advantage of FWD is interior space. No large bumps in the floorpan are required to accommodate mechanical parts. Look at current Honda Civics, and you will find great rear seat room in a small vehicle because of a flat floor pan. With no rear differential, trunk space can also be increased.
The disadvantages of FWD are mainly the decrease in vehicle handling ability. With more weight over the front of the automobile, the back end tends to become very light. Rear tire traction is decreased and the car may swap ends on icy roads easier. This has been overcome by designers somewhat by placing as much weight as possible further back in the vehicle. Ideal weight distribution is often described as 50/50 front to rear, but FWD cars seldom get near this.
Another disadvantage is the load placed on the front tires. They must transfer all acceleration, steering, cornering, and braking forces to the road. The tires have only a finite amount of grip, so using some of it for acceleration must decrease it in other areas. The rear tires have very little load on them and are basically only along for the ride. This is why accomplished FWD racers say “put the gas to the floor and steer – the rear will follow”.
All the disadvantages of FWD systems are advantages of RWD vehicles. With some of the mechanical parts removed from the front and installed at the rear, vehicle balance and handling are much improved. Using the rear tires for acceleration traction takes the load off the front, so drivers accelerating out of a corner have much more lateral grip. RWD is used on all the world’s fastest road course race cars and many performance production vehicles for this reason.
Repair costs are another advantage of RWD systems. Although costs vary greatly by make and model, if you have transmission problems with a RWD vehicle, the cost of differential repair is not required, as it might be on a FWD system. The reliability of FWD cars has increased so much over the decades, that this might not be a big concern.
Disadvantages of RWD are higher assembly and production costs, more parts to have problems with, and less interior room in the vehicle. Independent rear suspension, used on many current RWD cars allows the engineers to position the body closer to the differential and driveshaft, so interior room has improved.
Traction has always been a problem with RWD vehicles, because of the lower rear vehicle weight over the drive wheels, but modern electronics has changed that. Traction control and vehicle stability systems enable RWD cars to rival FWD vehicles on slippery surfaces. Improved tire designs have also helped.
Even with the decrease in passenger compartment room and increased mechanical complexity, I am still a rear wheel drive fan. I guess I just like the feel of the handling when pushed into corners. Other very good drivers I know would disagree with me.
So what is the answer? How about all wheel drive! Porsche uses AWD on a Carrera model to enhance performance and traction. Subaru has won several world rally championships with all wheel drive. The debate on what drive system is best still continues, and probably will for as long as we drive.