The sleek Infiniti G37 Cindy Marsh bought last August was the car of her dreams, equipped with the latest keyless electronics technology that allows her to start the engine with the touch of a button.
But right away, the system gave her trouble. To get the engine started, she would sometimes have to tap the power button repeatedly. Sometimes it wouldn't start unless she opened and closed the car doors, Marsh recalled.
She eventually adapted to the system's quirks but said that even now she isn't sure how to shut off the engine in an emergency.
"I don't know if I ever read it in the owners manual or not," said Marsh, who lives in Columbus, Ohio.
Old-school car keys appear headed for extinction, as automakers rush to install wireless systems that allow drivers to unlock their doors and start their engines with an electronic fob that they never have to take out of their purse or pocket.
Introduced less than a decade ago on luxury models, the push-button systems are rapidly spreading to all segments of the market, including bargain-priced Kias. The number of models with them as standard or optional equipment has quadrupled in the last five years.
Many drivers don't fully understand how the systems work, however, leaving them vulnerable to potentially serious safety problems.
In complaints to federal regulators, motorists have reported that they were unable to shut down engines during highway emergencies, including sudden acceleration events. In other cases, parked vehicles accidentally rolled away and engines were left running for hours without their owners realizing it.
And although traditional keys all work the same way and are universally understood by consumers, automakers have adopted different procedures for using the keyless ignition systems. As a result, owners may not know how to operate their own cars in an emergency, let alone a rented or borrowed car.
"Where you have a second to make an emergency maneuver, you shouldn't have to search around for the right procedure to use on a switch," said Henry Jasny, general counsel at Advocates for Highway and Auto Safety, a nonprofit group based in Washington, D.C., that pushes for laws to make roads safer.
The risk is considered serious enough that federal regulators and an auto industry trade group are looking at adopting standard procedures.
All of the systems rely on a similar architecture that uses a fob: a small transmitter that communicates with the vehicle's computer. The fob can automatically open door locks when the owner approaches the vehicle, and then the engine can be started with just the push of a power button on the dashboard.
But to shut down the engine while the vehicle is moving, drivers must hold down the power button for one to three full seconds, depending on the make. In some cases, two or three successive taps on the button will work. Mercedes-Benz allows drivers to kill the engine with a single push of the power button, but only if the transmission is in neutral. At least one manufacturer prevents emergency engine shutdowns if the vehicle is moving at less than 5 mph.
Industry officials say that the devices have become wildly popular with buyers and that glitches will be eliminated through the normal course of technological improvements, making new regulations unnecessary.
"We really haven't seen too much confusion with these systems," said Dave Proefke, a vehicle security engineer at General Motors Co.
"As they become more widely adopted, I think we'll find that they converge in how they operate," he said.
Besides offering convenience for motorists, Proefke said, the technology gives auto designers greater styling freedom because there's no longer the need for a key cylinder in the steering column. It also benefits older people who have difficulty removing keys from their pockets or turning a key in a lock.
And "it has that cool factor," said Dan Edmunds, director of vehicle testing at www.edmunds.com, an Internet automobile research site.
Auto safety experts say the industry needs to do a better job explaining the functions of advanced technology to motorists and needs to adopt common operating procedures.
Automakers are offering the systems on 155 models this year, compared with 41 in the 2006 model year, according to Edmunds.com. Ford Motor is planning to make keyless ignition an option in its entry-level 2011 Fiesta, due out later this year.
But some owners say that confusing software rules have put them in peril.
Wally Brithinee was in his 2007 Toyota Avalon last August when it began to speed out of control on Interstate 5 near San Diego. Thinking quickly, Brithinee, president of an electric motor repair business in Colton, pressed the sedan's power button, but nothing happened.
"This car isn't stopping," he told a passenger as he felt panic swelling in his chest. "I really didn't know what to do at that point."