发表于 2009-05-14 14:27 IP属地：未知
Front Wheel Drive
Around since the 1920's, front wheel drive didn't catch on with American consumers until the gas crisis in the 1970's. As Americans struggled against high fuel prices, automakers began to seek new ways to increase fuel efficiency. The best way of course was to reduce the size (and thus the weight) of most vehicles. As Detroit aimed to make cars smaller, they needed a more efficient layout that would yield more interior room in a smaller package. Front wheel drive was the solution. By placing the engine and transaxle in the front, there is no large transmission housing or driveshaft tunnel running through the passenger compartment. In addition, engines were positioned transversely to reduce the size of the engine bay. And there was another advantage as well. With 60% of its weight at the front, 40% at the back, fwd holds an advantage in slippery conditions such as ice or snow as more weight is over the drive wheels reducing slip during acceleration.
But most of the advantages end there. As most of the weight in up front, a fwd car is not as well balanced therefore it doesn't handle quite as well. Also, as vehicles continue to become more powerful, front wheel drive becomes more of a liability. Torque steer (when the steering wheel pulls to one side during acceleration) is a serious issue with many front wheel drive cars that exceed 250hp. As such, we've seen a resurgence in the popularity of rear wheel drive in more powerful vehicles.
Rear Wheel Drive
Prior to the fuel crises in the 1970's, rear wheel drive was king. Just about every vehicle, from economy to luxury, came with rear wheel drive. The shift from rear wheel drive to front took about a decade. Since the mid eighties, just about every economy car, family sedan, minivan and even many sport coupes came with front wheel drive. Luxury marks such as BMW and Mercedes-Benz continued on with rear wheel drive but Cadillac eventually moved every vehicle to front wheel drive. Once again, times have changed. Over the last few years we've seen more and more vehicles (re) introduce rear wheel drive. Why? Well, it simple.
As cars become more powerful it is difficult to have one set of wheels doing the steering and the accelerating. By having the front wheels do the steering, and the rear wheels driving the car, you get a better-balanced vehicle. This eliminates torque steer and improves acceleration. Rear wheel drive offers better weight distribution (much closer to 50/50 than fwd), which in turn offers more predictable handling. Finally, with the advent of traction control and stability management systems, the front wheel drive advantage in slippery conditions has been significantly reduced. More and more rwd vehicles have the option of AWD as well. If nothing else, this is a great way for automakers to hedge their bets. Still, some consumers are skeptical of rear wheel drive. Perhaps they are the victims of clever marketing by Madison Ave. that tried to get people to accept fwd and forget all about the virtues rear wheel drive. They did a great job. Perhaps too good.
Today cars are more powerful yet yield better fuel economy. As such, we can look at fwd and rwd more objectively. Is one better than the other? Fwd still holds an advantage in terms of packaging efficiency, offering greater interior room in a smaller package. Rear wheel drive provides better handling and acceleration and with the addition of traction control, virtually eliminates the fwd advantage in the snow.
In the end, it depends on what you want from your car. If it's performance, you're looking at rwd. If you're indifferent, perhaps looking for a small car with greater interior volume, it's front wheel drive for you. Over the last 20 years, technology has improved both layouts, reducing the advantages of fwd to a point where rwd is a viable option for most people. Ultimately, you've got more choice, and when more choice is offered we all win.
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