Why would two cars that are nearly identical with similar miles and offered in the same area have very different average market prices?

It seemed to me that your "statistical" market price for my car was way lower
than it should be.  Nonetheless, I listed my car on CarGurus -- at more than
$800 over the "market" value.  Two weeks later and not one single inquiry.  
Now that my car is listed on CarGurus.com, though,  I see other cars that are
the same make model,year, and with similar mileage that are priced
significantly HIGHER than mine and are shown as "lower than market".  It
seems that your "statistical market" values are not consistent and maybe
even favor dealerships.