Yes, to answer your question the reliability of Cap One Auto Navigator is high. I would think the only reason for rejection at the actual dealership would be because between the time of the soft pull Cap One does to pre-qualify, and when you take the HP from Cap One at the dealer, something deragatory happened.
As far as terms (APR), they can sometimes change when you are at the dealer, the pre-approval tool assumes a set sales price to determine the APR, if the dealer is unwilling to negotiate to that price, or you lessen the down payment, or change anything in the structure the APR will more than likely change.
