U.S. Patent Nos. 6,346,876; 6,756,885; 7,671,727; and 8,032,278 are directed to remote control or monitoring of vehicle functions of multiple vehicles (page 2).   CalAmp sells the transmitter and receiver in the vehicle but not the transmitter and receiver on a cell tower for system claims, so there is no direct infringement (page 9). 

Hindsight: At least some independent claims may be drafted from the perspective of the device likely to be sold and controlled by one party, such as claims directed to the transmission to the cell tower and receipt from the cell tower without positively reciting the cell tower.  The server may be included in the claims, assuming the manufacturer of the car part controls the server.  Thus, the overall system may be protected without reciting parts likely to be out of control.