You'd probably have to find do the math. You could buy the car with 0% interest. But with depreciation you may or may not be that much ahead in a couple years for an 06. It would also depend on the interest you would get on an 05. I saw $2500 rebates on the 04 today. But I don't know if the would include the 0% financing.
The dealer I ordered my 05 from advised me to sell my 2000 ASAP as they will decrease in value once the new body styles hit. Just my 2 cents worth.
I am debating just when to start trying to sell my car as I don't want to be rideless too long.
I too was debating so much on buying a 04 GT or waiting for the 05.
Last Sunday on 4th of July, I bought a Black 04 GT premium package for $21,000. I got such a great deal I couldn't pass it up. $349 a month, can't beat that. They gave me the $2500 rebate and 0% finance and then I worked my magic from there. It was the last GT hardtop they had, all that was left was V6 and convertibles, and of course 04 Cobras, but those were out of my budget.
I plan on trading it in for a 2006 in a couple of years.