First of all, if history tells us anything, it's that when it comes to technology, car dealers are usually among the last to adapt. Social media is/will be no different.
Secondly, too many dealers want that report that you speak of, Jeff..."how many cars will this sell me this month?" From a dealer's perspective, I can understand this. They want ROI, and they want it immediately. Social media simply does not provide for an immediate ROI.
Dealers need to approach this topic more as social branding and engagement, as others have stated, not as social media. All of the tools and applications available with Web 2.0 make it easier and more cost-effective than ever to brand your business and engage your customers. In fact, other than time, using Web 2.0 tools cost virtually nothing. Dealers need to see the big picture and look at the long term ROI possibilities, rather than the "how many cars will this sell me today?"
Think about it. The traditional media (TV, newspaper, and radio), while they may allow you to help build your brand (less and less every day), do any of them allow you to truly engage and interact with your customers? No. Furthermore, with the Internet, DVR/TIVO, and satellite radio, how many people is your brand actually reaching? Fewer than ever. Yet, these media remain very costly.
Until dealers learn to adapt more quickly to changing technologies and changing culture, they will continue to spend their resources that provide for immediate (albeit significantly smaller) ROI, rather than the longer term (and potentially much higher) ROI.