Are kelley blue book values accurate and reliable? Kelley Blue Book is a very good resource, but it should not be the only one you consult. Although none of the top used car buying guides is perfect, when taken together – along with additional information gained from other websites – they can provide reasonably reliable and accurate information for your used car transaction.What are kelley blue book values? The Kelley Blue Book vehicle value is a fair sale or trade price determined based on the make, model, age, mileage and features of a vehicle, according to the Kelley Blue Book website. This value can fluctuate based upon the market and demand for the vehicle.What is kelly book blue? Kelley Blue Book is an Irvine, California-based vehicle valuation and automotive research company that is recognized by both consumers and the automotive industry. The company is owned by the Cox Automotive subsidiary of Cox Enterprises.