According to AutoTrader.com's 2015 Automotive Buyer Influence Study, the adoption of mobile devices for car shopping is increasing at a rapid pace. The study shows that 42 percent of recent car buyers used multiple devices to shop for cars, compared to the 24 percent who used multiple devices in 2013. The increase in mobile device usage is being led by used car buyers, who showed the most significant increases in using smartphones and tablets for car shopping.

"The power and proliferation of mobile devices in the U.S. is undeniable, and consumers are rapidly turning to these devices as they shop for cars," said Jared Rowe, president of AutoTrader.com. "The importance for all automotive advertisers to have a robust cross-platform presence cannot be underscored enough if they want to reach and influence consumers as they shop for cars."

The use of smartphones and tablets for car shopping both saw significant increases among recent buyers who used the Internet to shop for cars. In the 2015 study, 39 percent reported using a smartphone, compared to just 19 percent in 2013. Among those who use smartphones for car shopping, 65 percent use the device while visiting a dealership. For tablets, 35 percent reported using a tablet in the 2015 study, compared to 19 percent in 2013. Additionally, 25 percent of tablet users reported using that device while visiting a dealership.

Along with the ascent of mobile usage in car shopping, the study also found a slight — but notable — decline in desktop/laptop usage. In 2013, 91 percent of car buyers who used the Internet to shop for cars reported using a desktop/laptop. In the 2015 study, however, that number decreased to 82 percent.