Truth of the matter is; any listed "invoice" price is a scam and a lie. It's not the whole truth.
Basically invoice sets the base price to start the negotiations for anyone who knows that number. MSRP is for others.
Problem is; "invoice" isn't what the dealer paid and isn't the whole picture.
The key is to email or contact multiple dealers asking for the best price. The trick is to find one(ideally at the end of the month for example), that really needs to make a sale and will sell the vehicle off at almost any price just to make the sale so they can get their sales bonus from the manufacturer for meeting their sales target that month or quarter. They won't care about the $1,000 or $2,000 you saved when they have a check for hundreds of thousands if not millions on the way. That is how the dealers operate these days.
Just how many thousands less you can get the vehicle for under the published invoice price is anyones guess. Maybe it comes down to how much you feel is a good deal. Is $1,000 less enough or will you not settle unless it's $4,000 less?
Call this guy and talk tactics with him:
http://fightingchance.com/Also consider getting the vehicle from another town or city or even out of state if the price is that much lower.
True story: My brother in law was purchasing a new Ford Focus for the company he works for(for a sales person). He called all the local dealerships in the OKC area. $16k was as low as they claimed they could go. Nope, no lower than $16k just can't do it. Called a dealer in Stillwater, OK. $14k.