A system for regulating the operation of an idling motor vehicle monitors one or more selected engine operational parameters such as coolant temperature, exhaust gas temperature, and catalytic converter temperature, and compares the measured parameters against selected benchmark criteria stored in the memory of a microprocessor. The microprocessor controls the vehicle's ignition system to shut down the engine when the measured parameters come within the corresponding benchmark criteria. The system preferably but not necessarily operates in conjunction with a remote vehicle starter system. The system may also or alternatively be adapted to shut down an idling motor vehicle engine when total idling time reaches a specified maximum value, which may be selected based on idling time restriction bylaws. Accordingly, the system promotes reduced fuel consumption and mitigates environmental impacts by automatically regulating vehicle idling times, while also facilitating avoidance of idling time restriction bylaw violations.