Do you still use the radio or CD player in your car or do you prefer to use new portable media devices like smartphones? A new study from the NPD has found the answer and it may suprise you.

The NPD Group has found that the popularity of using portable media devices is growing. How much has the use of these devices grown? NPD’s retail tracking service pegs the sales of devices that allow the integration of media players with cars at more than $170 million in 2011.

The study, “Mobile CE: A look inside the vehicle,” found that 84 percent of vehicle owners have a portable media device whereas 79 percent of vehicle owners are using them in their car. The devices are also used regularly with half of smartphone owners and 37 percent of iPod owners saying that they use their devices “always” or “most of the time” while driving.

The study doesn’t spell doom and gloom for traditional car audio products, however, with 73 percent of vehicle owners saying they use the FM radio on car trips. Interestingly enough, 57 percent of consumers said that the presence of a CD player will be very important in making the decision of which car to buy next.

“Traditional radio and CD audio remain firmly entrenched in the vehicle from both a device and entertainment standpoint,” Ben Arnold, NPD’s director of industry analysis, said. “But as ownership of mobile devices, digital content, and apps expands, consumers will be looking for ways to customize the in-vehicle environment with content and services.”

Auto manufacturers had better start putting in-vehicle connectivity in cars as 32 percent of consumers now look for that as a key component to their purchase decision.

The way consumers are connecting these devices to their vehicle has become more varied as well. Eighteen percent of vehicle owners have an auxiliary input while 11 percent are connecting via USB. Wireless connectivity is also gaining ground with 13 percent of vehicles now sporting the function. More than half of vehicle owners who have built-in bluetooth or wireless systems say they use it most, if not all, of the time.

“The key is for auto makers and traditional audio manufacturers to facilitate consumer use of connected devices in the vehicle, allowing content from the smartphone, tablet, or digital media player to easily stream or be controlled through the deck mounted in the dashboard,” Arnold said. “We’re only going to see greater consumer attachment to social media, streaming audio and video, and other services as content options grow.”

We reported back in January that such connectivity is what led auto manufacturers to show up at CES as they demonstrated their new smart cars that promise not just smartphone connectivity for media, but a whole variety of apps including Facebook and Twitter.