Just call and say "blah blah dealership offered me $750 over invoice. If you can do $500 over I'll bring my business to you guys instead".
Edit: that only works for new - and also typically near the end of the month is better. Salesmen will take mini's easier if it'll bump their numbers up or put them in a new pay tier.
xbox 360: ImTooNiceAtThis
Last edited by benjamin1; 10-10-2012 at 06:36 PM.