No it doesn't work that way. If you get $15K for your trade in, it goes towards the $19K you owe on the loan. You still owe $4000 which get rolled into the price of the new car, raising the price above the sticker value. Your $15K from your trade in will not go towards the purchase price of the new car.
Cards: Orchard Bank ($1100) | Cap1 Cash Rewards ($2500) | Chase Freedom ($1000) | Best Buy ($2500) | Discover It ($1000) | Barclay Rewards ($2500) | Current scores: EX FAKO: 684, CK TU: 649, FICO EQ: 680, FICO TU: 698, FICO EX: 658 Happy Homeowner Since 2/6/13! 
Last App: 4/5/13 Gardening until July 2014
