cockroaches taking over my car!

why are there freaking cockroaches in my bloody car??!!! i've come across tiny probably still baby cockroaches scurrying across the dashboard, the handbreak, and the wheel of my car WHILE driving and it is really driving me nuts! i'll be attempted to squash those little maniacs WHILE driving and it's not an advisable thing to do, i know..but it's just so bloody irritating. so i'm determined to find the source of this infestation in my car by first spraying almost half the can of Ridsect's Cockroach Kill...i'm expecting to see a whole lot of dead cockroaches tomorrow morning. hopefully it even managed to destroy the palace of the king cockroach. in my mind, i keep picturing there is like a sarang or something under the seats which i have not dared to search for..

so WHERE in the world do the cockroaches come from? i'm guessing from the traces of kids' milk which they so often deliberately or not deliberately spill/squirt while in the car. i really have to get to the bottom of this. the feeling of driving a car with cockroaches just running across your fingers at any moment is really not a comforting one.