Derf00

This, yes. Private party, don't go dealer. Depending on your state you may be able to avoid sales tax by going private party. Here in AZ if you buy private, you don't pay sales tax or dealer fees.

DPE

I have always considered 'out the door' what I walk out of the dealership having paid. In my state, you pay sales tax and registration etc. at the DMV, or at least I always opt to if it's a choice. Given how different states do things differently, I assumed we were just talking about the price of the car itself. OP might want to make it clear what he's thinking on that based on the rules in his state, so we can all be talking about the same thing.