If the inquiry is for an auto loan then it shouldn't immediately affect your score Understand that wherever you are getting your EX score from (even here at My Fico) DCU is likely to pull a different version and it may be slightly higher or lower. In any event you can always talk to them after they pull your report and see what can be done to get you to the best rate. Often if things are close as far as score a financial institution can find "compensating factors" to sweeten an offer.
I have no personal experience with DCU so I don't know if they are sticklers with no leeway. But another member who does will certainly see this post and comment. DCU has a lot of fans in these forums.
Starting Score: 500's