I just got this from my credit union. Many credit unions are now open to (semi public) county residents. You just have to live in their county etc..
http://www.lovemycreditunion.org/Auto_Discounts_For_Con... 
Want to do your part to Invest in America and get a great deal on a new vehicle – all at the same time? You’ve come to the right place.
Credit unions throughout the United States have partnered with GM and Chrysler to help give credit union members a boost during these tough times. Depending on which vehicle you choose, you could save up to thousands of dollars on a brand new American-made vehicle.
And when you finance your new vehicle through your credit union, you’ll be saving even more with our fantastically low loan rates. On average, a new vehicle loan through your credit union is 1% lower than at other financial institutions. Another great reason to Invest in America.
Get started to driving your discount. Find out more about GM and Chrysler’s individual discount offers by choosing one from below.