Dearest Dave
Little do you realize that you are actually the easy sale, when you come in with numbers ready for a "Car Guy" he is going to sell you, you are doing my job for me by telling me exactly what you want and how much you are going to pay... If your numbers are way outta line I am going to show you the real numbers and if you don't believe me I will let you walk "Most" dealers don't sell at a loss :) (there are certain times where a dealer might sell you a car at a small loss to make a sales quota bonus)
When you "Walk" it is actually you who are losing the deal, if you want the best "deal" simply look at the Sales Leader in the paper and go buy it for a new car/truck, that is the one that has been stripped of all profit, in fact at some dealerships the salesman that sells it gets a $50 ding because he was too weak to move them off that car :)
New Cars and Trucks are easy to buy at invoice, there is no trick, just ask to see the invoice, any reputable dealer will show it to you, and you can get it easy enough online anyway... Heck some dealers are even offering 1/2 of the holdback to make car deals..
Even used cars are easy to get a good deal on, with all the online resources on value out there.. The days of jacking the price over book are long gone... Dealerships make their money in the "Buy" on used..
You just have to make sure to have a Title Search done ie: Carfax et al to check the VIN and for any discrepancies and for salvage..
Car selling and buying has changed drastically with the advent of the internet there is no reason to make it adversarial..
Now the guy that does F&I hehehehe with that guy you better be on your toes, there is money to be made in the dealership in the F&I dept.
Simply put, anyone that walks into a dealership without first being Pre-qualified by their own Credit Union or Bank is a whale to be landed in F&I and even there you are protected by Federal Laws the days of stacking huge money in points are also done..