Again...do your homework. FMCC probably not be competetive with local sources. Make sure you take into consideration all the programs that are available. For instance...if you finance with FMCC at regular rates...you may qualify for a small rebate in addition to the Customer Cash...generally $1000.
I would suggest that you probably would be better off taking all the rebates...finance with FMCC...and then pay off the loan after a short term...2-3 months...by financing with your local source. Your local source should still give you a new vehicle rate...and you still get the largest portion of the bonus rebate for financing with FMCC.
Hopefully this makes sense to you.