My uncle was a top car salesman in his area at that time. He said guys would come swaggering in with a printout from the internet, and he'd be like "so what - go somewhere else, then" because it didn't matter - no one was going to sell you the car at zero profit.
If they "secretly" raised the "invoice" price it was almost certainly so they wouldn't have to deal with boneheads constantly coming in and demanding to buy the car at cost.
Anyways, his advice today? Lease. And if you're trading in, wait until the day you're supposed to pick up the new car, then call in and say, "you know, I think my trade-in is worth more than that" - they will always negotiate at that point.