The Indipod, made by Bromsgrove-based Daycar, is aimed at people with bowel and bladder problems.

The chemical toilet is housed in an inflatable "bubble" which is powered from the car's cigarette lighter.

It is designed to be used in multi-purpose vehicles, four-wheel drives and estate cars.

The Indipod is on display at Naidex 2005, an exhibition of products for disabled people at the NEC in Birmingham.

When not is use, the Indipod folds away into a bag the size of a suitcase and weighs 8kg.

"When we developed it we thought it would be for families, kids going out for the day or on holiday," Daycar managing director, Barbara May, told the BBC News website.

"But we've had an excellent response from people with medical conditions."

European odyssey

To show of the potential of the Indipod, Daycar did a seven-day trip from John O'Groats to the southern tip of Italy without getting out of the car.

"For people with bowel disease, incontinence or bladder problems, this product is not a luxury, it's a necessity," said Mrs May.

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The company says that the chemicals break down waste into a "sweet smelling, inoffensive liquid", which can be disposed of at the end of a journey.

It says that there is no residual smell in the vehicle once the Indipod has been used, and that one sachet of chemicals is enough for one person's use for about eight days.

The bubble or "private sanitary sanctuary" inflates to an area about 1.2m high by a metre wide and is sufficient to accommodate two people, according to Mrs May.

"You could have a parent and child or a disabled person with a helper," she said.

If there is luggage or shopping in the back of the vehicle the bubble expands around it and occupies only empty space.

Once it is no longer required, the power cord is disconnected and it can be packed away into its bag.

It is thought that up to a million people in Europe have either bowel or bladder problems. Daycar says it has already received interest from people in Belgium and Italy.

Perhaps the most far-flung and unusual order came from a man in Australia who wanted to buy an Indipod for his wife's birthday.

Naidex 2005 is at the NEC from 24 to 26 May.