A little more than five years ago, two teenage girls, Amber Nicole Dibibar and Kerri Driscoll, were heading to their jobs at a daycare center in a front-wheel drive Ford Escort. They were making their way through a squall of wintry mix, well within the speed limit, on a suburban street in Franklin, when Dibibar lost control of the car on a patch of slippery road and was broadsided by a Jeep. Dibibar was seriously injured; Driscoll (known to her friends as “Sunshine”) was killed. Dibibar had hardly recovered from her injuries when she was charged with vehicular homicide.
But instead of charging the teenager with a crime, the authorities might have pointed the finger of blame at car makers and drivers’-ed schools who have been ignoring some inconvenient truths about popular — and profitable — front-wheel-drive cars for decades. The record of the Dibibar collision is ambiguous (she was cleared of all charges in 2004), but, working from circumstantial evidence, there’s a good chance the cause of this accident, and thousands of others each year, wasn’t driver negligence but poor driver training and a paucity of safety information from the auto industry.
What’s that, you say, front-wheel drive is unsafe? How can that be, if front-wheel-drive cars are known for their ability to handle snowy driving conditions, the likes of which Boston’s seen so much lately? True, compared with rear-wheel-drive vehicles — which ruled the road from the Model T through the 1980s — front-wheel drive offers a comfortable and responsive driving experience. They can also get through snow a lot better than their predecessors did because several factors, primarily the weight of the engine above the wheels that are pulling the car, improve traction.
Just because they might have an advantage moving forward in snow or slush, however, doesn’t mean front-wheel-drive cars stop in poor conditions or handle wet or icy curves any better than other cars. In that sense, front-wheel drive provides an illusion of control and safety that can dissipate in an instant.
Accident statistics gathered by groups such as the Insurance Institute for Highway Safety don’t focus on the model or drive train of vehicles involved, so, currently, evidence supporting the idea that mishandling front-wheel-drive vehicles is responsible for crack-ups is anecdotal.
But, actuarially sound or not, there are abundant reasons to be suspicious. Armchair analyses of accident reports in the media can be compelling. (And as a former ASE-certified auto mechanic, I do have some expertise in this area.) For example, as reported in the MetroWest Daily News, in May 2003, Tereza Pires was driving along notoriously hazardous I-290 near Worcester when she “hit a puddle near the side of the road and began hydroplaning, leaving her helpless to stop the minivan from careening off the road and rolling over several times.” One can’t help but speculate that, if Pires had been trained and understood the special dynamics of front-wheel drive, she might have used the engine's power to regain control. Instead, she most likely fell back on the traditional responses to loss of traction: taking her foot off the gas or stepping on the brakes. As a result, Pires and two family members, including her eight-year-old daughter, lost their lives.
The physics of driving a front-wheel-drive vehicle differ from those governing steering with rear-wheel drive. As Jonathan Linkov, managing editor for automobiles at Consumer Reports magazine, explains, all cars exhibit characteristics called “neutral steer,” “understeer,” and “oversteer.” Neutral steer means you point the wheels and the car goes exactly where you expect it to. At low speeds, most cars neutral steer.
At high speeds, or on imperfect road surfaces, though, they usually understeer or oversteer. Understeer is the tendency for a car to turn less than you expect in relation to how far you’ve rotated the steering wheel. This is what most cars do on a smooth, dry road when they are being pushed — that is, moving too fast and/or making a corner that’s too sharp. A driver can usually sense understeer coming on and can get back to neutral steer just by slowing down a bit.
Oversteer is just the opposite — the car responds to steering by turning more than the driver expects. Oversteering is dangerous because it can happen quickly and it’s easy to go from oversteer into a skid or a spin.
In normal circumstances, most front-wheel-drive cars exhibit moderate to mild understeer — making them a little clunky, but safe. But sometimes at higher speeds, or during high acceleration in turns, front-wheel-drive vehicles can oversteer, usually causing the car’s rear-end to start to slide. This isn’t dramatically different from what happens in a rear-wheel-drive car and, under normal circumstances, you can regain control just by slowing down.
All of this goes out the window, however, on slippery surfaces — particularly snow or ice — or even on a dry surface if, for any reason, a car’s tires start to lose their grip. Then, if the driver backs off the gas, things could actually get a lot worse.