Correct, but "invoice" is a convenient shorthand when you're comparing prices people got for different trims and options.

For example when I was shopping for my 4Runner there were options I had to have (e.g. the third row) and options that were, er, optional (e.g. running boards). I got offers on slightly different vehicles from different dealers. Thinking in terms of over or under the invoice was convenient for comparing how hungry or greedy the dealers were.

I wasn't trading anything in, so the number I cared about was OTD before sales tax and DMV fees (I was buying out of state). I ended up getting my truck for almost exactly invoice + a doc fee (and the dealer ate the cost for the pre-installed fluff like clear paint protection, nitrogen tires, etc. -- I was very clear that it is worth nothing to me and I am not going to pay for it).