A kill switch is the best protection, but they do make relays that are remote activated by cell phone or a separate fob.
Amazon.com: SinoTrack ST-907 Vehicle Car GPS Tracker, Car Relay Anti Lost Alarm Locator Real-Time Location Remote Control Cut Off Oil and Power Device for Car Motorcycle Truck Taxi, Support Platform : Electronics
NoStart Remote Controlled Intelligent Relay w/ Remote - Starter/Fuel Pump Immobilizer - Mobilistics™
Amazon.com: SinoTrack ST-907 Vehicle Car GPS Tracker, Car Relay Anti Lost Alarm Locator Real-Time Location Remote Control Cut Off Oil and Power Device for Car Motorcycle Truck Taxi, Support Platform : Electronics
NoStart Remote Controlled Intelligent Relay w/ Remote - Starter/Fuel Pump Immobilizer - Mobilistics™