Invoice price is a myth. The outed and lurking dealers here and elsewhere will fight tooth and nail to disagree, but no dealer pays jack squat for the cars they move until the end of a sales cycle. At that time, if a dealer has moved (sold) X number of cars then they get "billed" for the cars minus their operating costs. This is a positive figure and is called profit.
Dealers are franchised agents selling cars for the manufacturer. They don't actually buy the cars from VW more than they sell them for a gamut of figures their buyers somehow reach equilibrium with and sign their deals. The "invoice" price is a ficticious number artificially lower than the manufacter's suggested retail price (MSRP) that are both engineered to give buyers a sensation of power in their knowledge. Anyone paying less than MSRP but some menial amount over or under invoice is simply wandering through carefully planted figures nowhere near the actual dealer cost... a figure you'll never know because the dealers don't know it until they tally up all the sales, including yours, during a sales period. Rest assured it is nowhere near "invoice" because that figure itself represents a very generous though average amount of profit for the dealers.
Paying "invoice" is paying the desired average profit the dealers have agreed they'd like after moving some target number of a fleet of vehicles. Don't want to pay that? You have to find a dealer willing to average his profits, literally spread the profits from one or more other sales onto yours to give you a killer deal waaaaay under "invoice."
How do you get that you ask? Well, it takes a little patience and a lot of contact. Each dealer has a table of numbers of cars they want to sell by the end of the sales period. On the table are progressively lower "prices" for the cars they'll bay back to VW which goes down as their numbers of sales go up. They're not actually paying, but keeping more of the deal totals for themselves as profit. Sell more cars, send less money to VW.
No one of them will openly reveal they're on a timetable to sell as many cars as they can, but at the end of it the deals are more likely to appear. This is where patience pays off. You set your price and then stick to it until one of your local dealers feels the pinch to move just that one more car. They all see you waiting patiently with your far lower than average price offer and then start examining the sales they've already made. One of those dealers may grow willing to slice into the profits already garnered from a recent sale and agree to your deal just for the sake of moving one more car off his lot... and thus not having to split as much of the sales with VW.
None of those dealers may play though which is again where patience is a requirement. Meanwhile, the contact has already been made. If there's anything car dealers do, it's stay in touch. You have to be prepared for a lot of phone calls and emails, so you may wish to limit your contact info to a celphone or throwaway email to contain the spam. Dealer salespeople also seem to be pretty adept at appearing inept online conveniently forgetting what you're looking for and any prices you've discussed. You keep your wits about you and politely refresh the conversation with past information. Remain polite when you insist upon your price too. Eventually, the end of the sales period will arrive and the dealers will be flocking to you to see if you've found your car. Just stick to your price and one of them will probably badly want just one more car for their numbers.
It has worked for me. Two weeks of negotiation and polite eye rolling as dealer after dealer ping me to see if my price point isn't flexible... and then the offer comes. It sounds so awful and I'm stealing bread from their children's tables but the absolute best they can do is within a few hundred of my offer... but a Grand Canyon less than "invoice"... and includes my state taxes and registration fees. Instead of paying all the taxes, they're effectively paying half and, frankly, that impresses me and I'm inking on the other half.
It'll be a black DSG'd GTI and I'll have a scant seven weeks for break-in before I take the new ride to VIR for two days on the full course with Audi Club. Boo yah!