I am sitting here reading all of these responses and I can't for the life of me figure out why you would let a third party, much less a third party like Edmunds have access to your DMS. For a few internet leads. Really? How about this do marketing, prospecting, SEO, PPC if you need to and leave these parasites like edmunds, autotrader alone.
If you are a dealer go into your DMS and pull every deal from the internet and then compare that to deals from Radio, Direct Mail, referral, walk in and prospecting to see what your true ROI is.
Nice article Jeff.