we cannot jump to conclusion without much information.
apart from earlier information in the above post . we also need to know following
1) database size
2) transactions per day ,
3) type of transactions are they mostly query based or
heavy insert , modification also needed .
4) can the data from one dealer be available to the other dealers in other regions after certain taime lag ( for refresh )
5) should all the information be applied to all the dealers all the time ?
6) archival strategy for records .
7) are individual applications ( for various dealers same ? )
if there is any database difference , then just common tables can be centralised and remaing tables can be distributed ..

hope u are getting the point .