Most new car pay plans hover around 18% up to 30%. New car pack will vary from $0 up to $800. That means invoice is $16,494 on a base S and if the dealership packs it $500 it doesn't matter if you sell it for MSRP or not, you're only getting paid a flat for it.
I can sell you a full equipped Titanium and at my dealership the most I'll make is $400 in my pocket. In the internet day and age I start at invoice as a price, if other dealers want to hold to MSRP power to them, but they won't touch the volume that we will and in the end I'll have the happier customers because they are getting the product they want at dealer cost plus fees.
Plus it's important that people here realize that not all sales associates are there to rip your head off, I work my ass of and sometimes only make $100 on a sale.