i negotiate as two transactions, i dont set foot in a dealer until ive got an acceptable sales price over email, which is never more than invoice minus rebates. even if they sell below invoice before rebates, they still make money on the car due to holdback and floorplan incentives, not to mention sales quota bonuses etc., and all the service and potential financing charges they will get over the next x years.they make plenty at invoice or even below.
i then work trade, and point blank, i dont take anything less than high nada/kbb trade, plain and simple. they are gonna stick my immaculate car on the front row for high retail every single time, so i wont take it up the butt on the trade. the trade is worth what its worth based on book value, if you dont pay me that, someone else will. why on earth would i take less than what its worth? i always print kbb/nada trade values before i go to the dealer because every single time they will under option your trade and come back saying its worth $3k less than the printout in your pocket. they do this EVERY time, so know your own trade value and call them on it and pull your little printout out. then they will go oh well comps in the area arent selling for the high retail price listed right next to the trade value on your little pocket printout. then they start to pull printouts off the computer of lesser optioned cars, at which point you pull the same printouts out of your pocket of these same cars with scribbled notes about the options they dont have compared to yours, then pull out true comps optioned like yours selling for the high retail on your little pocket printout. you should know what comps in the area are selling for and have printouts in your pocket. they can make $1000-$1500 on my trade, but not $4k-$6k, sorry. dont get greedy, then you make zero dollars on two lost sales. the dealer is allowed to make money, but not too much.
trade and new car are two completely separate transactions. this state does have the tax credit when trading in, so ill factor that in when i consider what i could get for the car privately or would need to get to effectively get the same price as if i were to trade. ive sold enough cars and dealt with enough lowballing scum that i really dont care to sell privately. its can also be tough to sell a car privately if you have a lien on it.
remember - they need to sell you a car, you dont need to buy one. so why roll over? they will make money on both sales every time, and they constantly lie about everything, so stick to your guns. zero reason to get whacked on either end of the deal when you dont need to buy a car in the first place and even if you do absolutely need to buy there are a million dealers willing to sell you one. for this reason i also dont give a crap if its end of the month or not, shouldnt be waiting til the 31st to hit your quota.
ill finance with the dealer for covenience if they match/beat my credit union. my credit union wont do 0%, but a lot of dealers will so then its a no brainer. ill finance wherever the rate is best, plain and simple. currently have 0% through vw on my wifes beetle, its great.
for what its worth on my last car, i bought a '14 mustang gt premium. i special ordered it and got it for invoice minus rebates, which came out to $7k off sticker for a special order. did this over email/phone before going to a dealer or mentioning trade. once i got a price i liked from a good sales guy, i went in to meet in person and ask a few follow up questions on the order process. i then said i had a trade and we went to look at it. my trade was a '13 Jetta SEL w/nav, which stickered around $27k and I paid somewhere a little under $24k new (less markup on a VW but still paid below invoice). bought it new, drove it for 16 months and 20k miles, and traded it in for high nada trade value of $17,300 (and dealer locked it in in writing at time of mustang order) saving tax on $17,300 on the mustang, making the effective trade price around $18,500. for comparison, vw dealers were listing certified jettas (which ford couldnt cpo it) like mine for asking prices of $19k at the time, so i did excellent on both ends of the deal. i actually suspect ford was lucky to make $500-$1000 on it. cant really complain when you buy a new car for under $24k, trade it after 20k miles and only lose a quarter of the value when dealing with new car depreciation and trade lowballing.