The eBay Motors site is far and away the most popular automotive-industry website, accounting for nearly 20% of all traffic to the category, according to Hitwise:
Download the Excel file of the above data.
The Hitwise data featured here (Top 15 US Websites, July 2009) is based on US market share of visits, as defined by the IAB—the percentage of online traffic to the domain or category—from the Hitwise sample of 10 million US Internet users.
Hitwise measures more than 1 million unique websites daily, including sub-domains of larger websites. It categorizes websites into industries on the basis of subject matter and content, as well as market orientation and the competitive context.
The market-share-of-visits percentage of certain websites does not include traffic for all sub-domains that could be reported on separately.