Affiliate is 1% below true invoice, employee is either 3% or 5% below (I don’t recall the current number) minus all rebates and incentives. With these programs that’s your price, no negotiation allowed or the dealer can’t submit the deal under the program and get their compensation (they get a stipend to make up the difference between invoice and the discount).
The only way a dealer can sell to you at a lower price is to either leverage a factory to dealer bonus they don’t tell you about (one they must disclose in a true employee or affiliate deal) or dip into their holdback (Google dealer holdback).
However, there are times of the year, usually near the end of each quarter, where they need to meet a sales quota to either qualify for a full holdback payout or get a significant bonus where they will sell a vehicle at a loss (start at invoice, subtract all incentives and subtract the holdback) to make their numbers. Sometimes losing $1000 on a few deals can earn them tens of thousands of dollars in bonus and holdbacks. If you’re lucky you’re the one buying one of these sacrificial lambs.
I’ve been buying under the various programs (affiliate, x plan, supplier) for 20+ years. The 2019 Long Horn I just bought was $51500 MSRP, affiliate was $47900 and there were $6500 in rebates and incentives. Bought the truck for $41400 + tax and tags. No negotiation, deal took 5 minutes to close. I’m pretty satisfied to save $10100 without having the break a sweat.