What website does car dealers used to get the book value of a car?

A friend of mine is trading her car and she did a Kelly Blue Book on her car and got the value but when she went to the dealer they told her they don't use KBB and that they used a different system. They appraised her car at a lower value than KBB and now I'm wondering what appraisal website do they use because KBB gave my friend a higher appraisal than the site that the dealer uses.