Developed by software engineers at Lysanda the technology plugs directly into the car's On-Board Diagnostic (OBD) port, analyses engine data and predicts emissions.

The gentle drive along B-roads and A-roads replicated a typical motorist's journey and it returned an average CO2 reading of around 170g/km --†some 43g/km more than the manufacturer's claim of 127g/km.

Hard acceleration pushed this figure past 390gkm -- more than the average CO2 output of a supercharged V8-engined Range Rover Sport --†but gentle coasting saw a reading of around 70g/km.

Commenting, a spokesman for Ford said: "The ability to hit the average CO2 targets we set as manufacturers is entirely within the driver's remit and anything that helps drivers to do this is to be applauded."