We all know that just having a website, no matter how great, is not enough to make sales in the automotive industry. LEARN MORE
Google+ is a little undesireable for car dealers because of the seeming lack of engagement there, and adoption is still very low even among those dealers who have already gotten into social media marketing. Google+ doesn't come close to the level of interaction that Facebook has, but it is still a very important place to be. Since Google moved places to Google+ Local now you have to have Google+ to have a local listing, and Google favors their own content when evaluating search and serving results so it has a clear SEO advantage as well.
Check out the full story about Google+ Marketing here.