SageStream LLC Gave me a bogus credit rating! San Diego California

I guess I should start by stating that your score without any context means anything.  Putting your Experian and TransUnion scores doesn't provide that since those scores are based on a different floor and ceiling than SageStream.  However, the average Experian and TransUnion score is 720, so your score of 653 tells me you have below average credit and you still have some work to do.

SageStream weights your credit score more on your overall history, than simply your recent history like Experian, Equifax, and TransUnion do.  In other words, if you have worked on your credit score to raise it from the depths of the deep to where it is today, then your hard work will be more positively reflected on Experian and TransUnion, than it will with SageStream.  If you found a dealership that uses SageStream, then you found a dealer that is looking for customers who have little to no history of bad marks on their credit.

The thing you should do, aside from improving your credit, is not to go to dealers that use SageStream and tell them you won't do business with them.  When enough people make the decision to follow your lead, and their profits drop as a result, then that will either force the dealership to change whom their partner with, OR SageStream will change their model.