A system for conducting wireless communications between a vehicle computer and a remote system includes a passive radio frequency tag attached to a vehicle and electrically connected to at least one vehicle computer via an information bus, and a tag interface unit electrically connected to a remote computer system. The remote system is operable to control communications with one or more of the vehicle computers via a radio frequency link established between the tag and tag interface unit. The tag preferably includes a microprocessor-based computer electrically connected to the information bus, wherein the tag computer operates as a gateway for communications between the remote computer and any of the onboard vehicle computers including a vehicle/engine control computer, an interface module computer and a transmission control computer. The system preferably includes means for notifying the vehicle operator of various statuses of the communications being conducted, wherein the remote system is operable to control such notifying means.