A calculator is just a tool to construct your own offer and/or recalibrate someone else’s shared deal for your own taxes, incentives, RV/MF etc if they are different.
I’ve rarely seen anyone make any further headway by decoding a dealer quote into the LH calculator. If it matches, so what? Math doesn’t lie. If it doesn’t match, so what? Dealers aren’t going to lower their offer because your calculator said so. Chances are, it was the consumer’s error. If not, GL getting a dealer to admit it was theirs.
To be very candid, the ship sailed once the consumer asked for a quote instead of presenting a well-researched offer of their own.