The very old may not be Public Enemy Number 1, but they are killing people as never before.

People on America's streets and highways.

According to a Carnegie Mellon University study, the fatality rate for drivers 85 and over is four times higher than it is for teenagers, who are usually pegged as our most reckless drivers.

Two examples include an 86-year-old man who drove his automobile into a crowded farmers' market in California, killing 10 people. And in one recent year in Florida - the US state with the largest per capita elderly population - drivers over 80 plowed into a Chinese restaurant, post office and state official's office.

In every case, the elderly driver told police that he or she confused the gas and brake pedals.

All of these drivers had passed written and visual tests. None fell asleep at the wheel, had been drinking, or was taking strong medications.

Millions of older drivers have never had so much as a speeding ticket in decades of driving. Many self-regulate themselves by driving less often and avoiding frightening high-speed highways. But they can still be a menace on neighborhood streets.

Few elderly drivers willingly hand over their keys. Their car is their ultimate, treasured symbol of independence and freedom.

They - and the organizations that represent them - insist that the test for one's fitness to drive should be the ability to perform, period, not chronological age.

But current research suggests that it is complex processing skills, not actual sight or hearing difficulties, that are the root cause of dangerous driving.

So some doctors and insurance groups are recommending that seniors take mandatory refresher courses in driving and tests for mental dexterity. Drawing a clock face with the hands in a certain position, for example.

The goal, they say, is not to take drivers off the road and give them one more reason to be depressed about getting old. Rather, it's to keep them driving, but safely.

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（来源：VOA 编辑：崔旭燕）