Can't remember where you parked at the airport? Meet the gadget that will find your car for you

But the nightmare of trudging around the car park, laden with cases, looking for your car will soon be over.

Heathrow is to become the world's first airport to install technology that allows you to find your vehicle simply by inserting your parking ticket into a machine that has a 32in screen displaying a 3-D map.

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At the start of your trip, the same technology will also lead you to the nearest empty space - again displayed on a screen map to save time and carbon emissions.

Technology giant Siemens has developed the system for the 3,800-space short-term multi-storey at Heathrow's new Terminal 5, due to open next March.

When a driver arrives at the carpark barrier, a numberplate recognition system takes the registration and automatically prints it on the ticket.

An information screen at the barrier tells the driver where to find a space and illuminated arrows on the floor act as a guide to the empty bay, which is marked by a green light above it.

The car is tracked by up to 35 infrared cameras which feed details of where it is parked into the system.

On returning, if drivers cannot remember their spot they put their ticket into one of 16 "car-locator" machines to view the 3-D map.

Each of the machines is 6ft high and will be at the entrances to Terminal 5 as well as on each floor of the new multi-storey.

Hugh Fenn, a spokesman for airports operator BAA, said: "Talking to our customers, the things they have found really important are the speed of finding a space and locating their car when they get back.

"Understandably they want to do that quickly. This technology is able to ensure people do that because it knows where their numberplate is parked.

"Once you put your ticket or registration number in the car-finder machine, the 3-D interactive map locates your car. On that map will also be access points such as stairs and lifts."

He added: "The technology is also extremely environmentally friendly. It stops people driving round and round looking for spaces, or stopping with their engine running while they wait for one.

"It helps the loading of the car park, therefore stopping congestion. Our research suggests this will reduce carbon emissions by about 397 tons a year."

The £4.2billion Terminal 5 building was given the go-ahead after the longest planning inquiry in history.

It is the size of Hyde Park in London and is scheduled to handle 30million passengers a year.

Ten football pitches would fit on each of its five storeys and the complex is the size of Gatwick, which would make it one of Europe's biggest airports in its own right.