Ford said its Sync radio system has been installed in more than 3 million vehicles, since it was first introduced late in 2007.

Ford first included Sync as a $395 option in its 2008 Ford Focus cars (launched in the fall of 2007). Today, Sync is available on all Ford and Lincoln cars, except those targeted for commercial or fleet use. Car buyers are opting to pay for Sync about 80 percent of the time on the newest car models. Ford says 80 percent of users recommend it to others, up 5 percent from a year ago.

The Consumer Electronics Association, which puts on CES, said in a 2010 study that 55 percent of smartphone owners say they prefer voice commands as their primary means of communicating in a car.

Also, more than 80 percent of Sync owners are likely to recommend the system to others, claims Ford. That's a 5 percentage point improvement over last year.

When we introduced Sync, we were committed to making voice recognition a highly useful tool for the driver, and this research confirms we're on track, said Jim Buczkowski, director of Ford electronics and electrical systems engineering, and research. Ford remains committed to being the company that will continue to raise the bar on voice recognition as the primary user interface - giving customers the connectivity they want while helping them keep their eyes on the road and hands on the wheel.

Another study that looked into integration between smart phones and in-car connectivity devices in 2010 showed that more than half of the people who use smart phones prefer as their main user interface voice commands.  This research was conducted by the Consumer Electronics Association and published with the title Staying Connected on the Go: A Look at In-Vehicle Smartphone Integration Systems.