The dealer only uses your rate to know what car to put you in.
You NEVER want to show or drive someone in a loaded Mercedes’ when they can only buy a Ford Taurus. If you do they’ll spend the next six weeks trying to get the Mercedes

Never come back
In the end the dealer isn’t giving you the loan
He’s just trying to make as much on the loan as humanly possible
In an annual report one of the big public auto companies reported making 1600 average per car in finance alone
Considering tough educated customers and cash customers they make zero to average 1600 they make 3,000 on others