Royal protection officers are road-testing a bulletproof, anti-kidnap, gadget-laden limousine for use by Prince Charles and Camilla.
The £300,000 BMW 760 is loaded with security features including windows and bodywork capable of repelling gunfire.
Prince Charles and the Duchess of Cornwall became startled backseat targets during student protests in London in 2010.
The Independent newspaper reported their Rolls Royce was pelted with eggs and paint bombs and Camilla was poked with a wooden pole through an window as crowds chanted "off with their heads".
Remote ignition means the BMW can be started from a distance in case terrorists have wired explosives to the starter system.
Sensors are in place to detect and automatically extinguish fires underneath the vehicle and in the engine bay.
In the case of a gas attack, windows and air vents are automatically closed while a supplementary oxygen system kicks in.
The boot of the car can be locked and unlocked remotely by police so it is impossible for royal passengers to be trapped inside.