ive had this happen to me once, due to my cousing (grrr). i knew where he was and pulled the dash apart and got him out by tugging a little bit.are you sure you checked everywhere in your dash? other than that all i can think of is hed be somewhere in the car, like under the seat. you could try leaving a warm mouse in there, or depending on the size of your BP, run an extension cord into your car window (make sure your window is closed as much as possible) and plug in a heat pad set on low with a hide box over it, and the mouse in it. but if its a small BP i wouldnt do this seeing as how he could get out of it. im sure other people will have ideas. is there anyway he could get into the trunk, or maybe hes behind part of the dash and you didnt see him?