I sold cars for a while... Tell them about your trade after the final offer, Cause you will fuck their system all up.... But they wil prob give you less for your trade you wont really win. Check NADA.com for your car value and go off that. Kelly blue book is based out of Cali, and there cars are worth more than here due to us having salt, more rust ect. So if you base your car off of Blue Book standards you wont be happy. But this is just what I know. good luck.