Hello, I program in the google maps api, to cut it short I can easily create an app where your users will be able to zoom in on where they live and markers will pop up where dealers are located, and once they click on the dealers there is a popup speech bubble where you can have info such as address and store times. You (the admin) would have a system where you log in and enter the address then what appears in the text box, the address would be posted to yahoo (they offer better geo coding which means address to lat and longitude service)and posted to your database which will isplay the info on the map . The google logo would appear in the bottom left for legal reasons and you would register an 'access' key so your site can access google maps (easy and free.) I hope this is what you want and I think your consumers would really appreciate it.
Max, FuN DESiGNs