1. A method for deferring a telematics data upload from a vehicle equipped with wireless telephony and wireless networking communications devices, comprising the steps of: (a) detecting the availability of a connection to one or more wireless networks along with an associated time of day during which the connection is available; (b) determining that a particular one of the one or more wireless networks is periodically available at a particular time of day; (c) receiving a request to upload data from the vehicle to a central facility via a wireless telephony connection; (d) delaying the data upload until the particular time of day; and (e) uploading the data to the central facility via a wireless network connection to the particular wireless network determined in step (b).