Cash vs outside financing, they won't give a damn one way or another, either way THEY get paid in full when the car leaves the lot.

Now Cash vs Dealer financing, it just depends. some would rather have the cash, and some would prefer you to finance it b/c they make money off the interest. just depends on the dealer. but my guess is paying cash is a lot LESS of a bargaining tool than it might've been a long time ago.