The car business is too decentralized and redundant to have one company control the market's indices.
But, dealers tend to think alike and industries have communication outlets. Automotive News is the bible, and there are different sections which address parts of the car bid-ness such as manufacturing, retail, auction, lending, etc. You can project a trend based on articles from several sources amalgamated into this one publication.
I agree with this video wholeheartedly, I actually think we're about to see not just a "normalization" of the market but.......a DIPbefore the "normalization"