JAGUAR has unveiled its most efficient engine yet in the form of a new 2.2-litre diesel unit.

Developing 190 PS and 332 lbs ft of torque, the new engine is capable of returning 52.3 mpg on the combined cycle while emitting 149 g/km of CO2.

It’s been fitted to a prototype development vehicle, with a new intelligent Stop-Start system to operate more efficiently.