“Is that your car out the front? We can give you $15K for it.”
Your answer? “Thanks, I may consider that. But I want that to be separate from the pricing of the new car.” They can easily inflate the price of your trade to make it look like a bargain, but then inflate the new car price and you will not notice this as it’s a ‘change over’ price you are given. TIP: Keep it all separate.