This news was published recently at seroundtable and it was originally shared by gfiorelli1 on Twitter.
Google had recently added automobile related information on its Knowledge Graph and has soon started to test ads displaying nearby dealers when someone is searching for specific car related information.See an example of Knowledge Graph getting displayed when someone is searching for 2014 Honda Accord. (Since Google is still testing the ads so you won’t be able to see the ads right now.) Soon knowledge graph would be having ads.
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