- The Washington Times - Friday, September 21, 2001

Recently a friend came up with a list of potential vehicles to replace her ailing clunker.

She narrowed the list down to a few very good sedans. In discussing the differences and merits it was mentioned that the one she was most interested in was rear-wheel drive. "No," she exclaimed, "I didn't think anybody built rear-wheel-drive cars, I assumed all cars were front-wheel drive by now. That car won't work well in winter will it?"

Not long ago all vehicles sold in the United States were rear-wheel drive. What happened? Was front-wheel drive that much better? The answer is yes but not because front-wheel drive offers better driving performance. In reality, manufacturers needed to reduce the size and weight of their vehicles in order to help meet federal gas mileage mandates.

But Americans still desire big cars. So the manufacturers found a creative solution. Front-wheel drive is nearly a packaging miracle. It places the entire drivetrain up front, which allows as much interior and trunk space as the next size larger rear-wheel-drive car can. The modern front-wheel-drive layout was first popularized in the British Mini, enabling it to comfortably fit four persons in a car only 10 feet long, and this breakthrough eventually made the minivan so versatile. A front-drive powertrain enables an easy step-in height, lots of people and cargo space, and flat load floor. Despite the popularity of sport utility vehicles, minivans still are the best all-around family haulers.

So what did the friend decide? After more discussion of the differing characteristics, she became comfortable enough to settle on the rear-wheel-drive car that she really desired. What were the magic words that assuaged her fears? Well there's no real magic to it, just some very basic concepts.

First under normal driving conditions in good weather, and following domestic traffic laws, most drivers won't notice the difference between front-wheel drive and rear-wheel drive. And even in adverse conditions, with the advent of traction-control and stability-control systems the differences in the two drive schemes may no longer be noticeable to the casual driver. Without these driving-assist systems the differences only become a factor under more severe conditions, such as inclement weather or racing.

Let's discuss weather first and in particular snow and ice. Tire adhesion and traction is the key to good adverse-weather performance and these give you the ability to accelerate, stop and steer. There are a number of ways traction can be optimized for adverse conditions and most of these advantages are built into the car. One is to have sufficient weight over the drive wheels. Most front-engined cars have most of their weight on the front wheels, this includes both front-wheel-drive and rear-wheel-drive cars. With more weight to help plant the front wheels, a front-wheel-drive car can have a traction advantage in snow and ice.

Remember how people used to add weight to the trunk of the car in the winter? That was an attempt to increase traction in rear-drive layouts. Pickup-truck owners typically put a couple bags of sand directly over the rear axle to help increase traction. (If you have a front-drive car, don't bother as it is of no help and will even make winter handling worse.)

But the best way to increase traction in snow and ice is to have proper snow tires fitted. A good set of snow tires is decidedly superior to all-season tires in snow and ice on any vehicle. In fact a set of four good snow tires on a rear-wheel-drive car can be superior in snow and ice to a front-wheel-drive car with average "all season" tires. Whatever the configuration, put the best tires on the front, as these wheels perform the important tasks of steering and most of the stopping.

Racing has a different set of priorities and when there are no restrictions, race cars will most often be rear-wheel drive. There is a division of labor between the steering wheels and the powered wheels in a rear-wheel-drive race car that is advantageous, especially in high-performance cornering and acceleration. It allows for a sharper-handling edge.

Do you remember some of the high-horsepower front-wheel-drive cars of the 1970s and 80s? They had an unsettling tendency to tug the steering wheel heavily when power was applied vigorously. That phenomenon is known as torque steer and while modern front-wheel-drive engineers have pretty much exorcised that demon it still matters in racing.

Aware of this principle, most sports cars, sports sedans and even luxury sedans employ rear-wheel drive. For sports cars and sedans with their slightly more enthusiastic drivers, rear-wheel drive provides them a bit of a performance edge.

For some reason the marketplace expects that luxury sedans will be rear-wheel drive when in reality they could be front-wheel drive without any problem. This is probably due to a European bias toward performance driving, and Mercedes-Benzes, BMWs and Jaguars set the trends at the higher end of the marketplace.

Note that after many years of fine front-drive luxury cars, Cadillac and Chrysler are planning on rear-wheel-drive layouts for their future top vehicles. In reality, this is due more to snob appeal than functional benefit, and they will lose floor space in the bargain.

So evaluate your driving requirements, when possible test your choices in the conditions you expect to use them and opt for traction- and stability-control systems if available. The best of all possible worlds is all-wheel drive, but that's a different article.

LOAD COMMENTS ()

 

Click to Read More

Click to Hide