Updated

In the age of adaptive cruise control, lane departure warnings, and self-parking vehicles, many drivers are confused about one simple operation: shutting down the car in an emergency.

Tim Brennan, a former police chief, says he has only used a key and prefers that for his personal car. Most of the drivers FoxNews.com consulted said they also prefer to use a key.

The issue is an important once, say experts, because the vast majority of drivers in the US are used to a normal key to start and turn off a car. Yet, newer keyless-entry systems, where you hold down the brake pedal and push a button to start the car, are becoming common, if not standard in many vehicles.

Now, the National Highway Transportation Safety Administration (NHTSA) has proposed that every automaker follow the exact same rule about how to turn off a car. The proposal, which has not been finalized, suggests a half-second shut-off after pressing the engine start button. That way, experts say, even if you borrow a car, rent one for the weekend, or buy new, every car will work the same.

The NHTSA report suggests new alerts that warn the driver when the engine has been disabled, and a warning for other drivers if the engine is still running but the driver has exited a vehicle.

Steven Stepanian, a driving instructor at Driving Concepts (www.drivingconcepts.com), an organization that runs driving clinics for teens, says there are many situations when having a fast shut-off is better than just shifting into neutral or coasting. He says humans have an autonomic muscle reaction – an instinctual reaction to do something the same way every time without thinking.

In most cases, one obvious button to turn off the car, he says, would make sense because we tend to react suddenly – we want to just disable the car in a panic situation, not think about options.

“The faster you can get the car disabled, the faster you are out of danger,” he says. “If the situation is such that you need to shut down the power to the engine or electric motor, you want it done as soon as humanly possible. I can't come up with a reason that you would want to delay that action.”

Jakob Nielsen, a usability consultant, told FoxNews.com that a standard half-second shut off in cars makes sense especially for those who are in the first few weeks of driving a new car.

“Having the same design will dramatically increase the chance of the button being employed fast enough. Furthermore, there is the problem that in a panic situation non-trained people don't think clearly, which would be an argument for going with the 1/2-second activation.”

However, he also questioned whether the half-second panic button makes sense in every situation.

“Such a short activation period involves a substantial risk of accidental activation if people press the button by mistake. I think this is unlikely to happen while driving, but even a small probability could lead to more accidents than would be prevented by a more reliable shut-off procedure.”

Thilo Koslowski, a Gartner automotive analyst, welcomes the new NHTSA proposal. He says a standard push-button for turning off a car could go a long way in saving lives, especially in those cases where someone panics and wants to just turn the engine off and coast to a stop.

Koslowski says the biggest challenge with new cars is educating drivers on how they work. In Some Lexus and Mercedes models, the engine start-stop button only works if you hold the button down for about three seconds. On other brands, like Ford and Chevy, the shut-off works in a half-second. Interestingly, Chrysler has avoided the problem altogether: they still use keys you must insert.

None of the automakers  FoxNews.com contacted would comment on the validity of a standard panic button in cars, although Toyota issued a formal statement on the issue:

“We are reviewing the NHTSA notice of proposed rulemaking for Theft Protection and Rollaway Prevention and plan to comment to the NHTSA using the prescribed process."

Koslowski says a common engine start button is even more important with electric cars, since you can’t hear the motor running and it’s harder to tell if the motor is running. He says there should be additional indicators, such as chimes and lights that tell the driver the motor is not running.

Wade Newton, a spokesperson for the Auto Alliance, told FoxNews.com that they agency is still studying the NHTSA proposal and does not have a formal opinion yet. (The group represents multiple automakers.) He agreed that the proposal seeks a standard shut-off in the same way that seat belts have standardized into one basic design that works the same across all car companies.

Neilsen, says, ultimately, the auto industry might need to pick the lesser of two evils. A half-second shut-off might be the best scenario for most situations, even if it leads to the occasional accidental push. Because the latter situation is rare enough, the NHTSA will need to do extensive testing to determine if the risk outweighs the benefits.

Click here for more from FoxNews.com Autos