They use whatever score they use period.
However there are many FICO scores and captive financing at a dealer likely uses a FICO Auto Score.
Best bet is to know all your scores Mortage, Auto, FICO 8, FICO 9....
Then bring your own financing (unless it's 0% at dealer).
For example DCU uses your Equifax FICO Mortgage score which could be higher or lower than your FICO 8.
My other local credit union uses your Experian Mortage score.
What brand car (sorry if I missed it)?
Research in the forum what score that brand uses in your area and know that score.
Knowing your FICO 8 is only part of it.
Now also keep in mind a few things:
Dealers typically make money when they finance a car for you. If you are approved at 6% they may charge you 8% and pocket 2%.
Other dealers will fight to get you approved at a better tier.
There is no way they will use any other score than what they use period.
if your mortage scores are around there you should qualify for good financing at DCU maybe not their very best but probably around 5% for 84 months for example.
Good luck but know before you go.
Don't accept so-so financing if you can do better thinking you can always refinance because you may not be able to.
If you don't put a lot of money down you will likely be too upside down on the loan to refinance for a few years.
