To be fair mine via carwow was spec'd up quite a bit, not sure if that helped to increase the dealer's offered discount rate or not. I also negotiated direct with the dealer on a few things beyond the original carwow quote which all helped towards the final discount when I worked it out.
In my experience, whatever is bid online by a dealer can vary from day to day subject to their circumstances just the same as in the showroom - e.g. status of monthly quotas etc... so I wouldn't assume that their first bid for your business is necessarily their best and final.