Getting a good deal is not rocket science, but it does take research to figure out how to do it right. Most people are either lazy or unimformed and aren't willing to invest their time, even though they can save upwards of $5,000 on a typical deal.
Dealers sell vehicles every single day. They know every type of customer, all their objections, and tactics to pressure and profit from them.
A typical car buyer only buys a car once every 5 to 6 years. There's no way they're going to outsmart a dealer without being fully prepared.
But the statistics show that 80% of car shoppers try to negotiate at the dealership instead of doing everything via phone or email. They also finance their cars through the dealership and trade-in their old car without thoroughly shopping it to other dealers.
Of course, dealers love it because those are the 3 main ways they make money off of clueless shoppers.
Most car shoppers focus only on negotiating the price of the car. That's fine with dealers, because they can easily give you a good price while completely ripping you off on the financing and trade-in.
If you focus instead on your trade-in, that's fine too. The dealer will simply raise the price of the car and screw you on the financing.
The main point is that dealers will juggle these 3 profit sources so that you get a good deal on whatever you're focusing on, while being ripped off on the other two.
Always make sure you seperate each transaction into its own negotiation. Don't let the dealer package everything into one monthly payment.