flipped cracka,

It might matter. Sometimes the manufacturer will do whats called "subventing" the interest rate. When you see advertisements for 0.0% financing, it isn't because anybody is lending money for free -- its because somebody is buying down the loan.

The upshot is that you should ask the dealer what is the best interest rate they can offer and compare it to the credit union. Pick whichever one you like the best, but bear in mind that if the difference is half a percentage point, you're probably only talking about a difference of less than a few hundred dollars over N years.

Financing at the dealership could be more convenient by far even if it costs a little more.

Good luck.