How long does it take to get approved for an auto loan?

I went to GMFCU (general mills federal credit union) on Monday to get a auto loan for $10,000. I took my mom with too because she is co-signing because I have no credit and she has Very good credit. She was under the A+ category they have there. Well anyways they gave me an interest rate at 4.25% but they had to send the application to corporate to approve it. The lady said I should get an answer later that day or at the latest the next day (Tuesday). I called them on Wed. wondering if I got approved or not and she said there is no answer yet. So here I am still wondering if I will get approved or not for the auto loan. I told the guy I'm buying the car from I will have the loan by Wed at the latest because that's what I was told. I am afraid he will sell the car fast because its a really good deal. Does anyone one know how long it takes to get an auto loan approved? They are open only mon-fri so if I don't get it Friday, I will have to wait till next Monday and by then I'm sure the car will sell.

Golly, I can't believe it's taking this long! I got an approval over the phone the last time. Keep hounding them...or go elsewhere (bank, whatever) NOW!! Can you leave a down payment until you get approval? Next time write on the bill of sale, subject to credit approval.
Good luck!