(FORTUNE Magazine) – No one can soothe the spirits of the weary traveler like a blithe London cabby -- just ask Caroline Robertson, an American audit supervisor for Chase Manhattan Bank in Paris. Laden with luggage, Robertson, 30, recently hopped a cab for Piccadilly Station, where she planned to catch a train to Heathrow Airport. ''It's pure folly to drag that bloody suitcase on the tube,'' said the sympathetic cabby. ''I'll take you straight to Heathrow.'' He kept insisting even after Miss Robertson explained that she didn't have enough British currency to cover the fare. At Heathrow the driver graciously accepted (pounds)15 for the (pounds)18 trip, then carried his passenger's bags to the check-in counter. ''Happy to be of service, luv!'' exclaimed the cabby, doffing his cap. That kind of royal treatment is extraordinary even by the standards of London, the Shangri-La of taxidom. But leaving aside such notorious cities as New York and Paris, civil cabbies and efficient service are the norm in most of the world's business capitals. Knowing the do's and don'ts, the cost and convenience of taxis in six of them, can take a traveler far. London's 13,000 limo-size cabs are a pleasure to step into, and most have a light for reading and a heater for the passenger compartment. Aspiring cabbies spend up to three years tooling around London on mopeds in quest of the encyclopedic familiarity with London streets known in the trade as ''the knowledge.'' To pass a battery of exams, they must memorize 480 runs within a six-mile radius of Charing Cross Station. Fares are reasonable. A one- kilometer (0.6-mile) trip costs the equivalent of $1.28, a five-kilometer (three-mile) ride $3.57, a bit less than in New York, where comparable trips will cost $1.80 and $4.50, respectively. Cabbies expect a tip of 10% to 15%. As in most cities, fares rise on evenings and weekends. Hailing a cab can be futile in the evening rush between 4:30 and 6:30, so many companies have arrangements with one of three networks of radio taxis, the largest of which is called Computercab. Even in rush hour, companies with radio-taxi accounts can usually summon cabs in minutes. A radio taxi charges an 85-cent premium. You can't pay cash; radio taxis bill the trip to the company's account. Next to London's sprightly service, Paris taxis are a downer. Leggy customers have to squeeze into Peugeot and Citroen compacts, behind the bucket seats. Drivers are often surly. Most cabbies refuse to take more than three customers, since they feel cramped with a passenger sitting up front. Besides, the seat next to the driver is often occupied by a growling dog. YOU CAN HAIL cabs or find them at 600 taxi stations at luxury hotels, famous landmarks, and busy intersections. Fares are reasonable, particularly for longer rides. A five-kilometer trip runs just $3.18, plus tip -- 10% is de rigueur. Empty cabs, the ones with their yellow roof lights fully illuminated, are murder to find when you need them most, during rush hours and from midnight to 2 A.M. on Friday and Saturday nights. Many hotels have subscriptions with cab companies such as G-7, which owns 1,200 radio taxis. The cabby charges the customer for the trip to the hotel, which averages about $4. He also adds 15% to the total fare. Frankfurt taxi service is a tribute to German precision and punctuality. Germany's financial capital boasts 1,700 identically shaded cream-colored cabs, most of them gleaming new Mercedes, Audis, and Citroens. To win a license, cabbies must show that they can navigate the shortest route from any major government or commercial building to another through Frankfurt's maze of one-way streets. Most drivers speak enough English to take directions or tell a passenger where to find a private club after the bars close at 2 A.M.

Hailing a cab is practically impossible because taxis flock to numerous downtown taxi stands. You can call a cab (the numbers are 25001 and 13001) or ask a maitre d', doorman, or receptionist to ring one for you. A one-kilometer ride costs $1.79, a five-kilometer trip $6.24. Germans usually tip a generous one or two marks (50 cents to $1) on short rides but won't raise the tip over $1 regardless of the tab. Most cabs take credit cards, including Visa, American Express, and Diners Club. In Rome taxis get the job done with freewheeling flair. The cabs are an assortment of Fiats and other subcompacts painted egg-yolk yellow. Most drivers know Rome's streets by heart and whisk passengers around town at terrifying speed, spicing the performance with honks, yells, and baroque gestures. Sit back and enjoy the show. The cabbies thrive on chaos and have few accidents. As in Frankfurt, taxis cluster at downtown taxi stations. In outlying and residential areas you will have to call a radio cab that charges for the trip to pick you up (the number is 3570). Fares are high for short hops but moderate for the frequent longer rides needed to get around the sprawling city -- a five-kilometer trip costs just $3.60. Tipping is unnecessary. Traveling to and from Rome's Leonardo da Vinci Airport requires special caution. On a ride from Rome to the airport, the driver has the right to add an $8.60 (12,000-lire) surcharge to the amount on the meter, usually about $26. Drivers often try to charge the same premium on trips from the airport, but don't pay it: The correct surcharge is $4.30 (6,000 lire). Watch out for hustlers with unlicensed cabs. As an airport sign warns, ''All roads lead to Rome, but be careful who takes you there.'' Tokyo taxis pay characteristic attention to amenities. A hydraulic door on the left side of the cab (the Japanese drive on the left) slides open and shut automatically. The seats are covered in fresh white fabric, and many taxis carry small coin-fed TVs. Passengers can flag a cab, find one at a downtown taxi station, or ask a hotel clerk to summon radio taxis, which start the meter only when they pick up the customer. Also ask the clerk to write down your destination in Japanese. Few Tokyo cabbies speak English. Empty cars are usually plentiful except in the hopping downtown district on Friday and Saturday nights between midnight and 2 A.M. At those hours you might land a cab by waving two or three fingers in the air, a signal you are willing to double or triple the fare. Cabbies don't expect tips, but like everything else in Tokyo, taxis are expensive. The fare for one kilometer runs $4.42. The 60- kilometer trip from Narita Airport to Tokyo will cost you $130, so take a bus instead; the fare is just $20. Singapore boasts the same comfortable, Japanese-made sedans as Tokyo at a fraction of the cost. Fares run just 73 cents for one kilometer and $1.33 for five kilometers, and tips are prohibited by law. As in Tokyo, you can flag or call a taxi or hire one at a downtown taxi stand. But you can indulge in the convenience of hiring a taxi by the hour without busting your T&E budget. Hourly rentals are negotiable between passenger and driver; most drivers will accept about $15 an hour. To win a taxi license, a cabby must speak at least a little English, but his pronunciation may vary radically from yours. To avoid ending up on Bridge Road when you asked for Branch Road, write out the address. No matter where you are, stick with licensed taxis and shun the so-called gypsies. Even a licensed cabby may mark you as an out-of-towner and try to cheat you. But if you conspicuously write down his name and number at the first hint of funny business, you may avoid being taken for a ride. BOX: HOW NOT TO GET HUSTLED AT JFK % New York's JFK International Airport is infested with dishonest cabbies who prey on inexperienced travelers and foreigners. In September, for example, a limo driver charged a Japanese businessman and his family $400 for a trip to Manhattan. When the businessman refused to pay, the driver collected by holding the family's luggage for ransom. Following a few rules will improve your chances of getting to Gotham unscathed: Take a yellow, medallion cab. These are the only cabs in New York that carry meters and can be legally hailed. Each has a lighted placard on the dash giving the driver's name and registration number.

Use a taxi queue with a dispatcher if one is set up at your arrival terminal. The dispatcher generally hands each passenger a slip of yellow paper giving guidelines for taxi use in six languages. He should also jot the cab's registration number on the slip. Tell the driver your destination clearly and confidently. You want him at least to suspect that you know where you're going and how to get there, so he'll be less likely to take a circuitous and more costly route. If possible, give him directions. Make sure the driver starts the meter when your trip starts. Otherwise he may try to talk you into a flat rate that he will say is cheaper than the metered fare but probably isn't. The trip from JFK to midtown Manhattan is about $22 plus tip, tolls (never more than $1.75), and small charges for baggage. Don't let the driver double-charge. If you are in a group or sharing a cab into town with a stranger, one fare covers the trip to the final stop. If the driver says otherwise, he's lying.