As our picture shows...

As our picture shows, the device uses a special kind of solid polyurethane foam moulded to fit snugly around the engine. The idea is that it prevents heat escaping overnight, so when you start the vehicle in the morning the unit is still warm, easing the ignition process and boosting fuel consumption by up to eight per cent.

It works on the same principle as an insulating jacket on a domestic hot water tank, and the inventors reckon it can even cut fuel bills by five per cent during the summer.

The thermal jacket has been developed by Professor Norbert Deussen at Cologne Technical College in Germany. He told us there are other benefits which make driving more comfortable. "It can help with soundproofing to make cars quieter, and the engine will reach normal running temperatures much quicker," he explained. "It means the vehicle"s other functions, such as interior heating and hot air for windscreen de-icing, will be available sooner." Engine wear and tear is also said to be dramatically reduced.

The casing material has been produced by Elastogran, a German company which already supplies plastic components to every major motor manufacturer. Its work is used by Ford, for parts of the interior of the Focus C-MAX compact MPV, as well as Smart for the roofless Crossblade. Prof Deussen has not revealed which models are going to be first to get the new engine jacket, but there is speculation that a large German luxury car maker is among the front-runners.