Invoice pricing is a fixed price, just as MSRP is a fixed price. When manufacturers offer an incentive for dealers to go below MSRP, that has no effect on the invoice per se, but the dealer could choose to go further below invoice than he would otherwise be comfortable doing, as he's getting a greater subsidy from the manufacturer to move a unit.
The bottom line always remains the same: try to get the lowest total cost (not necessarily price). If you get too fixated on MSRP or invoice, you fall into a trap like focusing on a payment instead of a total cost (which is even more common when leasing).
Employee pricing is around 4% below invoice price, which makes it a pretty solid starting point for negotiation when it's being offered from the manufacturer. This means the dealer is being subsidized to the tune of 4%+ to move the unit. This does shift the whole pricing scale downward, so you should be thinking about going 2-4 percentage points below that, which would be in the 6-8% below invoice range.
Thanks a lot! I figured that but just wanted to be sure. After the new year Jeep (lease) lowered their Residual Values, and now the Money Factor (interest rate) is super high, so the $325 a month payment I planned on in December is now over $400 for the same vehicle!