If you already know the make/model you want, I strongly reccomend you use the USAA car buying service. I have purchased a car this way and it was easy.
I went through all of the options, and printed vouchers for three different dealers for the option package I wanted. Of course, the exact package was unavailable, so I spent a little time emailing back and forth with internet sales managers on "out the door" pricing on some VIN options, and got where I wanted. I was able, using email, to knock the price down a bit further than the USAA discount. I ended up buying from a dealer about 3 hours away. I did the financing online with USAA, and got a pretty good rate in the low 3's. When you do the car buying stuff, it links you right to the loan app as soon as you finish. They actually use the car buying out-the-door price with an added margin, and give you approval up to that amount. It gives you a table of monthly payments based on term and down payment to choose from. You can choose 0 down payment if you want. you can't use your spouse's income unless they are on the app. I used just my own credit and income, and even though I have a mortgage it was no problem. YMMV
I showed up on pickup day with a payment voucher from USAA, signed paperwork, declined any add-on bs like third party warranties, and was out in about 30 minutes with a new Jeep for my wife.
About a year later I refinanced it down using Penfed and ended up with a 1.49% rate. Now that I am a member of Penfed I would use their car buying service, which I suspect is powered by the same company. Their rates are lower, but they don't go over 60 months without a major down payment... So if you want 100% over 72 months, USAA is likely better.
When I bought my truck, I allowed the dealer to run my credit for a comp bid against USAA's offer. I told them I had financing already, but would allow them to try to beat it. I didn't tell them the rate. They came back with 2.99% @72 mo no down, which was better than USAA's rate, so I went with it. That was underwritten by TD Auto Finance, who owns Chrylser Motor Credit.
1. Use the car buying service from USAA or Penfed. You get rate discounts when you do, and the hassle factor drops way down.
2. Go with Penfed if you can. With the CB discount, I've seen them as low as 0.75%.
3. Use USAA otherwise, and if you don't mind the extra inquiries let the dealer try to beat USAA's rate with Chrysler Motor Credit.
This method is a luxury afforded to those with financial know-how and decent credit. Take advantage of it.
Edit- One more thing; USAA used an EQUIFAX FICO. Penfed pulled EQUIFAX and I assume they used a FICO. The dealer pulled all 3 once, and I assume gave an auto-enhanced to Chrysler. I got 3 additional pulls courtesy of the dealer for Ally, BofA, & Bank of the West.
Good luck,
Technically after the ink is dry today at 4 is fine, but you're making a smart choice waiting till the check clears and you get keys.