I agree with the dealers here. Having sold cars before, if you give a shopper an ACV for their trade without being in front of them to block their exit from your dealership, most people will walk on an ACV figure. Like the dealer mentions above, I have NEVER given a trade value, much less an ACV, expecially over the phone, where the client said "that's very fair, I think my trade IS worth 4K less than what KBB says"
I'd love to track the data on that tool to see what the bail out rate is, and what the appointment setting percentage is once you give out an ACV!