A new study shows car buyers around the world, including in the U.S., are changing how they buy new cars and trucks. Multiple visits to a series of dealers are out, while the trend of consumers doing more advanced research ahead of buying a car is in. (Read more: Tesla up, Ford down: 'Consumer Reports')

"This is the most dramatic change we've seen in the auto industry and how people buy cars in the last 50 years," said Hans-Werner Kaas, McKinsey's senior partner. Kaas and his team conducted their study by looking at consumer auto buying patterns at dealerships around the world.

A sales representative assists customers at Golf Mill Ford car dealership in Niles, Ill. Tim Boyle | Bloomberg | Getty Images

The conclusion: Car buyers are doing more of their own leg work online and spending less time at dealerships. Fewer dealership visits The McKinsey report says the average buyer visits just 1.6 auto dealerships while car shopping, down from 10 years ago when buyers visited an average of five dealerships. "The consumer now has more information online and through other sources, so they do not need to visit as many dealers," said Kaas. (Read more: February auto sales beginning to thaw)

Simon Soaf, general manager at Mossy Volkswagen in Carlsbad, Calif., has seen the change. "Those days of going to six or seven dealerships to shop for a car are over. It is not going to happen again. Customers are more savvy," he said. Soaf says the internet has become a major player in driving sales. He estimates that almost all of the customers at his dealership has done some type of advanced research on their own before entering the showroom. As a result, fewer people are coming in to "kick the tires" and just look around as they did 10 or 15 years ago. "The business has changed," said Soaf.