"Hands on the wheel and eyes on the road" is the rule of thumb often touted by U.S. automakers as the best way to stay safe on the road.
But the AAA Foundation for Traffic Safety says people's minds have to be on the road, too, and the often complicated, hands-free voice systems in many cars are too distracting.
The group released new research this week that shows voice command technology like Apple's Siri, Chevrolet's MyLink, and Ford SYNC with MyFord Touch creates high levels of distraction in drivers that use them.
Researchers ranked distractions using five categories, category 1 being the least distracting, and category 5, the most distracting.
The research relied on heart-rate monitors and other equipment to monitor test subjects' reaction times while performing different tasks.
Listening to the radio was ranked a "category 1" distraction.
Composing a text message or email using in-vehicle voice technologies was ranked "category 3."
Using the Apple I-phone's Siri system was ranked "category 4."
The research found a wide range in distraction depending on the system used by automakers.
On a five-point scale, Toyota's Entune system was the least distracting, receiving a 1.7 cognitive distraction ranking.
Chevy's My-Link, however, created a high level of cognitive distraction -- 3.7.
Researchers say voice-recognition systems that are inaccurate are more distracting than systems that are very good at recognizing commands.
"We're really hoping that the auto industry and the manufacturers of the devices will join forces and develop different technology that's safer for everybody," says AAA Michigan spokeswoman Susan Diltz. "Technology should be as simple as turning on the radio."