If you have the money and you call it savings, or whatever, I would think that's what it's for, so go on and buy something. If you're worried about the huge interst you are going to lose out on from the savings, you should forget about that particular worry.
Whats was the implicit APR on the deal? or are you saying that you drive the best cash/trade-in deal and then switch to 0% finance over 4 years for 50% of the net cash payment at no interest cost?.
Just wondering