Buick ranked at the bottom of the list.
"There's a direct connection between manufacturers that utilize their digital showroom effectively and satisfied shoppers who then become buyers," said Arianne Walker, J.D. Power senior director of marketing analytics, in a statement.
More than half of shoppers who are "delighted" with their website experience say they are more likely to test-drive a vehicle at a dealership after visiting the site.
The J.D. Power 2016 Manufacturer Website Evaluation Study considered four areas: information/content, appearance, speed and navigation.
The study also found that younger Gen Y shoppers used digital shopping tools at a higher rate than older Baby Boomers during the car-buying process.
"These shoppers tend to show a more positive perception of a brand after the website visit compared with Boomers," researchers said.
The study is based on responses from more than 9,500 new-vehicle shoppers who expect to be in the market for a new vehicle within the next two years.
Edmunds says: Positive experiences on manufacturer websites tend to drive car shoppers into showrooms, a new study finds.