Pay attention to the price on the first car you have to buy, they raise the price of it so you acctually pay for the other car. The free one is a used one. They had an episode on CNN about that.
Around here there was a Nissan dealer doing a Buy a TITAN and get a VERSA free. I am not sure how the dealer ran it but the VERSA was free. My friend did it and got both.
We have a Dodge dealer doing the same thing, but you buy a quad cab, Not a mega cab, and then a list of new cars for free. The retail on teh new cars is around $20k. You do need to pay full MSRP on teh one you buy, and that dealer tends to have a lot of additional charges...