TAMANA, Japan - Two pedals, inches apart, one for gas and the other for brakes. For years, a Japanese inventor has argued that this most basic of car designs is dangerously flawed.
The arrangement, he says, can cause drivers mistakenly to floor the accelerator instead of the brakes, especially under stress. His solution? A unified pedal, shaped to accommodate the entire foot.
On the right side is an accelerator bar. Pushing down on the pedal at any point activates the brakes while automatically releasing the accelerator bar.
"We have a natural tendency to stomp down when we panic," said the inventor, Masuyuki Naruse, 74, who owns a small factory here in southwest Japan.
"The automakers call it driver error. But what if their design's all wrong?"
Yasuto Ohama, a security company executive whose car has one of the pedals, said he switched after his foot hit the gas instead of the brakes and he almost struck a bicyclist.
"I now have peace of mind, because there's no mistaking when there's only one pedal," he said.
Since at least the 1980s, researchers have pointed drivers' propensity to press the accelerator instead of the brakes.
In a 1989 study, Richard Schmidt, a psychologist now at the University of California, Los Angeles, described how disruptions to neuromuscular processes can cause the foot to deviate from the intended motion, even slipping from the brake to the accelerator.
And when the car accelerates unexpectedly, Mr. Schmidt said, even experienced drivers can panic, "braking" even harder.
The current standard pedal arrangement is a function of automotive evolution.
Drivers of Ford's 1908 Model T maneuvered an accelerator lever on the steering column and three pedals: for shifting gears, reversing, and braking.
Over time, the advent of various manual and automatic transmissions has required different footwork.
Mr. Naruse said that replacing standard pedals with his device requires no big changes to a car's braking or acceleration systems, and retrofitting costs about $1,156.
The biggest challenge of mass marketing the pedal, driving specialists said, would not be cost or technology, but the need to fundamentally change the way millions of people drive.