The report from Arbitron and Edison Research said 50 percent more people are listening to Internet radio through their car radios than last year, CEOutlook.com reported Thursday.
Seventeen percent of all cellphone owners have listened to online radio streamed in their cars this year through a connection to the radio, compared to 11 percent last year.
Online radio listening of all types, whether from a PC, car or portable, has now reached about 30 percent of U.S. adults and teens, the report found.
An estimated 76 million Americans age 12 and older are listening to online radio, it said.
"We've been tracking the usage of online radio in this series since 1998, and this year's increase in weekly usage is the largest year-over-year jump we've ever recorded," said Bill Rose, senior vice president of marketing for Arbitron Inc.