The uniformed men in fluorescent vests strip the car of its door panels, carpet and seat cushions.

They're not looking for cartons of cigarettes, drugs or even weapons, but wads of deutschmarks.

The traffic in smuggled money is nothing new, particularly among organised criminals.

But now the race is on to track down people with undeclared cash hidden away that will become worthless on March 1st next year unless they convert it into euros.

The so-called "money tourists" are on the move, customs officials are ready and a multibillion mark game of cat and mouse has begun.

Customs officials are on the look-out for cash amounts exceeding DM30,000 (€15,340) which, according to German law, must be declared when brought over the border. Of most interest are the border crossings to Liechtenstein and Switzerland, long-time favourite locations for Germans looking to hide money in secret bank accounts.

Last year, customs officers mounted more than 3,000 checkpoints and discovered nearly DM300 million in undeclared cash, one-third of which was destined for Switzerland. By mid-August of this year, customs officers had surpassed that haul.

German banks said earlier this year that they had recorded three times the average number of transactions with the hallmarks of money laundering.

Customs officers are also watching the border with Luxembourg. They have stopped growing numbers of Germans planning to open tax-free bank accounts for undeclared savings, which they hope will be converted to euros without attracting any attention.

In the tiny German state of Saarland, which borders with Luxembourg, customs officials netted more than DM6.5 million in the first three months of this year. More recently they have been bringing as much as DM10 million a month.

Now customs officials are working around the clock in roving teams, mounting blitz checks near border crossings. The checkpoint locations change daily but the procedure remains the same.

"As well as asking the right questions, experience plays a large part," says Mr Josef Krasmann, a customs officer working on the B51 motorway outside Trier, on the border with Luxembourg.

"You have to have a nose for it, have some criteria for judging and stopping cars," he says.

His criteria for nabbing "money tourists" are relatively simple: BMWs, Mercedes and Audis are always of interest, particularly if they have licence plates from distant cities like Berlin or Bremen, or are driven by middle-aged business men.

An elderly couple stand smiling by the side of the road as customs officers search their BMW.

"They seem to think we have millions squirreled away in Luxembourg and are on our way to add to our stash," says the man. "We often come this way and this is the second time we've been searched recently."

A few minutes later officials stop a black Opel. After speaking with the customs official for a few minutes, the driver says he has DM58,000 in the car. When asked where, a woman gets out of the passenger seat and gives the customs officer a cushion she was sitting on. Inside the cushion cover are thousands of warm, crisp DM1,000 bills.

Later on in the shift, three people in an Audi are stopped. One man is travelling with a kilogram of gold, worth about DM20,000. Despite being under the DM30,000 limit, the man's details are recorded and he is told to expect a call from the authorities.

A majority of drivers found transporting large amounts of cash tell similar stories. Money inherited from dead relatives over the years and never declared is the most popular excuse, say customs officers. Regardless of the source of the money, people face stiff penalties and hard-up German finance minister Mr Hans Eichel can look forward to an unexpected cash windfall this year. "I can only recommend people to present themselves to their local finance office before the end of the year," Mr Eichel said recently. "That way it's painless and carries no legal penalties, although the applicable taxes and interest of 25 per cent will be calculated retroactively and must be paid," he added.

By agreeing to repay the outstanding tax plus interest, in effect a form of self-prosecution in Germany, tax offenders can avoid a court action that could lead to a fine. The number of self-prosecutions has nearly trebled, from over 10,000 in 1998 to more than 27,000 last year.

Mindful of increased checks on the Luxembourg and Swiss borders, many Germans are seeking new hideaways for their cash. A new "find" is the northern Austrian mountain enclave of Jungholz, only accessible by car from Germany.

"One of the last investor paradises," said the town's Raiffeisen Bank in a recent brochure to potential customers. Here, 3,470 feet up, wealth can multiply "leisurely", deutschmarks will be changed into euros "discreetly and at no cost" and - most importantly - the money is out of reach of Mr Eichel.

After the unpleasant money business is out of the way, and the money safely deposited, the brochure encourages visitors to enjoy a "well-tempered cigar from the humidor" and "a relaxing massage on the chaise longue".

Reports of stricter checks on Germans bound for Switzerland and Luxembourg have been great for business, a banker in Jungholz told a German newspaper recently. Despite being located in a town with only 370 residents, the Raiffeisenbank last year reported a balance-sheet total of DM1.64 billion and predicts this year will be another year of record-breaking profits.

"Since there's no real border here, there are no checks," said one banker in the town. "The customs officials over the border in Bavaria can't keep their eyes open around the clock."

There is little or no danger of discovery of an Austrian bank account once a client exercises caution, he said. "Austrian bank secrecy is stricter than in Germany. To abolish it would require a two-thirds majority in parliament and that never happens."

The Germans now making their way to Jungholz are not all that different to the ones stopped at checkpoints in their BMWs on the borders to Switzerland and Luxembourg.

One recent German visitor to Jungholz was unrepentant when quizzed by the Frankfurter Allgemeine Zeitung newspaper.

"I haven't worked all my life so that politicians can ruin everything," he said. "But who knows where Hans Eichel has sent his spies."

Back at the checkpoint outside Trier, customs officers continue their work, sniffing out people unaware of, or unable to make the trip to the "investor's paradise" in the Austrian Alps.

Customs officers know, with limited resources, their spot checks can only ever scratch the surface of illegal cash transports in the next month. But they are hopeful their purge will lead to bigger discoveries, such as rings of money laundering, the profits of organised crime and drug dealing.

In the meantime, with the deadline for changing deutschmarks into euros approaching, they expect the number of German "money tourists" to continue increasing and for the schemes for smuggling money across the border to become even more outrageous.

"The best was the woman with over DM100,000 in her bra," said one officer. "A feat of engineering really, quite a wonderbra."